MINES DEPARTMENT: ELECTRIC POWER FOR DRIVING MINING MACHINERY (REPORT ON PRACTICABILITY OF USING, AT KUAOTUNU AND THAMES, BY THE INSPECTING ENGINEER, AND MR. R.E. FLETCHER, ELECTRICAL ENGINEER).

Appendix to the Journals of the House of Representatives, 1893 Session I, C-04

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1893. NEW ZEALAND.

MINES DEPARTMENT: ELECTRIC POWER FOR DRIVING MINING MACHINERY (REPORT ON PRACTICABILITY OF USING, AT KUAOTUNU AND THAMES, BY THE INSPECTING ENGINEER, AND MR. R.E. FLETCHER, ELECTRICAL ENGINEER).

Presented to both Houses of the General Assembly by command of His Excellency.

No. 1. Mr. H. A. Gordon, F.G.S., Inspecting Engineer, to the Hon. B. J. Seddon, Minister of Mines. Mines Department, Wellington, 22nd July, 1893. Sic, — Be Electrical Plant, Kuaotunu. In accordance with your instructions to examine and report, in conjunction with Mr. Fletcher, on the practicability of working the crushing-plants on the Kuaotunu Goldfield by means of electricity, I arranged with Mr. Fletcher for him to report on the electrical plant, the cost, &c, and I would report generally on the possibility of getting the water as the motive-power to generate electricity, and on the actual power required to work the whole of the crushing-plants on the Kuaotunu Goldfield. I have the honour to report as follows : — There are at the present time four different crushing-plants at work at Kuaotunu : namely, those belonging to the Try Fluke Company, with 11 heads of stamps; the Great Mercury, Mariposa, and Bed Mercury Companies, each with 10 heads of stamps, and Curtis's Battery with another 10 heads, making a total of 51 heads; there are also belonging to these companies 17 grinding and amalgamating-pans, 3 settlers, and 8 berdans. The power required to work the stamps, assuming the weight of each stamp to be 8001b., working with a drop of 6in., and making 90 blows per minute, would be as follows : x o.fiL —-— = 55-76 theoretical horse-power ; but about four-tenths of this power would have to be added for friction, which would make the power required to work a stamp-battery equal to about 78-horse power. The grinding and amalgamating-pans require about 4-horse power each ; therefore, 17 X 4 = 68-horse power required for the pans. Settlers require, say, 2-horse power each, and berdans os-horse power each to work them ; therefore, the settlers require 6-horse power, and berdans 4-horse power, making a total of 78 + 68 + 6 + 4 = 156 total power required. The motive-power at the present time is supplied by five steam-engines; and, unless the whole of these crushing-plants w r ere erected under one roof and under one management, the only saving that would be effected by using an electrical plant would be the amount expended in fuel. All other expenses would be about the same. Therefore, before going into the cost of motive-power to generate electricity, it might be well to observe that in order to reduce the cost of crushing to a minimum, it is actually necessary for the whole of the present companies to combine, and, instead of havingfive separate plants with five sets of men attending them, to have one central plant, andeach of the different companies to connect their mine with that plant, either by aerial or ground tramways. This in itself would lessen the cost of crushing considerably, even by using the same motivepower as at present, and the same thing would apply if the central battery were worked by electric motors. Although I have stated that it would require 156-horse power to work the present crushing plants on the field, two of these companies have abandoned the use of grinding and amalgamatingpans and substituted a Cassel plant; and since our visit to the field another company has arranged to erect a Cassel plant. Therefore a less power .than what I have stated would be sufficient to do the work, or, at least, there would be ample power to erect more stamps if at any time fresh developments were made. The question, therefore, at issue is : "Where is the place from which water can be obtained to generate the electricity ? After visiting the field, and having an interview with each of the managers of the mines, they deemed it desirable to work their present plants and not to erect a central one, merely having electricity as the motive-power. Mr. Fletcher and myself showed them that to do so not only meant a loss of power, but that the expense of working a central plant was about the same as I—C. 4.

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working one of their present plants. However, as the directors of the different companies are in Auckland, the mine-managers could do nothing but merely express their views on the subject. After meeting the managers we proceeded to Mercury Bay, and next morning went up to Gumtown, thence up the valley of the Waiwawa Eiver, in order to ascertain the practicability of lifting water from that river to get motive-power to generate electricity near Gumtown, so that sufficient power could be transmitted to Kuaotunu, a distance of about twenty miles. The Waiwawa Eiver is the only source from which a sufficient quantity of water can be got, and, in order to get water as a motive-power from this river, it would have to be lifted about 15 chains below the first branch of the river above the Eangihau Junction. I measured the width of the river at the point where the water would require to be lifted, and took the depth at every 10ft., also measuring the surface velocity at different places in the current, and found that there was about 2205 sluice-heads flowing at the time of my visit, and also about 31 siuice-heads in the Eangihau Stream, which would also have to be lifted. The quantity of water at the time of our visit was, however, much more than it would be in summer, and, therefore, a very large deduction would have to be made in making calculations as to the available motive-power during dry weather. From all information we could gather from the residents in the locality, it would appear that there is at least one-third the quantity of water in the river in dry seasons as there was at the time of our visit. If this information could be relied on, then a supply of 84 sluice-heads would be available in dry seasons. According to the barometer levels, taken on going up the valley of the Waiwawa Eiver to the point where the water would require to be lifted, it was 90ft. above the point near Gumtown where the electrical plant would have to be erected; but on getting down to the same place at night the barometer showed a difference of 12ft., the height being only 78ft., and any calculations made are based on the latter height, so that any errors will be on the safe side. The distance that the water would have to be conveyed in an open conduit and flume would be about five miles; the water would have to be lifted out of the south side of the Waiwawa Eiver, and conveyed for the 30 chains in closed boxing, having piles driven at intervals along the line of boxing, and the boxing securely held down so that floods could not lift or damage it. After the first 30 chains the water could be carried in an open conduit having a flume across the Eangihau Stream, and a branch race from that stream to join the main ditch. There would probably be a short tunnel through a rocky bluff, and possibly one through a narrow saddle; but neither of these would be of any great length. Taking, therefore, the length of the water-race as five miles, and allowing sft. of fall per mile, it would leave an available head at the terminating point of 78ft., less 25ft. absorbed in fall, or a hydraulic head of 53ft. Taking, therefore, the quantity of water to be one-third of that at the time of our visit—namely, 5+31 _ Q4 sluice-heads; and 84 sluice-heads with a hydrostatic head of, say, 50ft., that is allowing 3ft. of head to be absorbed in friction in the pipes at the transmitting point of the waterrace, it would give —-— 6 ° *v*—i-— = 4773 theoretical horse-power ; but, as it would not be safe to calculate on a water-motor giving more than 70 per cent, of the theoretical power of the water, this would give an efficiency of 334-horse power for driving the dynamos. But if even a further deduction were made in the quantity of water in dry seasons, and say that there is only one quarter, as at the time of our visit, then this would be 63 sluice-heads, and —° * — Z-zz. = 358 theoretical horse-power, and 70 per cent, of this gives the actual power transmitted by the water to drive the dynamos —namely, 250'5-horse power. Taking, therefore, the loss due to transmission of electrical power by alternating-current dynamos, motors, transformers, and on the line, the former calculation would give about 220-horse power, and the latter 164'5-horse power applied to the crushing-battery. Having shown that there is a water-supply to generate electrical power to drive the present crushing batteries at Kuaotunu, the next question is the cost of the plant, and the expense of working it. Calculating the cost of the plant, provision should be made to use the whole of the available water in the Waiwawa Eiver in dry weather. If it is found necessary, therefore, the open conduit, fluming, and pipes should be large enough to have a carrying capacity of 84 sluice-heads of notwithstanding the fact that 63 sluice-heads would be sufficient for the present requirements; the extra cost in the first instance is not great, and this would then provide more power for future developments on the field. The dimensions of the open conduit to convey 84 sluice-heads of water, constructed on a gradient of 1 in 1056, or sft. to the mile, would be Bft. wide in the bottom, 12ft. wide on the top, and 4ft. deep ; the fluming and boxing would require to be 9ft. wide and 4ft. deep. Of course a conduit and flume of much less dimensions would do if the fall were increased, but the object is to have as large a head as possible at the terminating point of the water-race, and, therefore, the gradient of the ditch and flume require to be kept as low as possible. The banks of the Waiwawa Eiver are tolerably steep all the way up, making it costly to lift the water from both the Waiwawa and Eangihau Streams, also, both these rivers are utilised for floating down kauri-logs in time of floods, so that the boxing alongside the river would require to be very strongly and firmly fixed to prevent the logs from damaging it, when coming down the rivers. These rivers in time of floods rise to a great height, so that covered boxing would have to be carried from the point where the water is lifted to above flood-level, and this would necessitate about 30 chains of boxing at the Waiwawa, and, say, about 20 chains at the Eangihau. It would be impossible to give anything like an accurate estimate of the cost of constructing this water-race without a proper survey being made; but, judging from the nature of the ground, I would estimate the cost of bringing in the water to be from £12,000 to £15,000, including iron pipes at the lower end. Taking, therefore, the estimate of Mr. Fletcher for the electric plant, the expense of erecting an electric plant to work the batteries at Kuaotunu would be as follows; —

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£ s. d. Cost of water-supply, say ... ... ... ••• ••■ 14,000 0 0 Turbines with belts, framing, &c, say .... ... ... 500 0 0 House for turbines and generators ... ... ... ■ ■ ■ 250 0 0 House for transformers at Kuaotunu ... ... ... 100 0 0 Electrical apparatus, poles, and insulating wires ... ... 6,553 0 0 Packing, freight, and general shipping charges ... ... 573 15 0 Freight and cartage from Auckland, 90 tons at £1 ... ... 90 0 0 Erecting pipes, turbines, generators, transformers, and line ... 375 0 0 Supervision ... ... ■•• ■■• ••• ••• 300 0 0 Incidentals 100 0 0 Total £22,841 15 0 Yearly Cost. £ s. d. Interest, 6 per cent, on £22,841 15s. ... ... ... 1,370 10 1 Depreciation, 5 per cent, on £9,341 15s. ... ... ... 467 1 9 Depreciation, 3 per cent, on £14,000 ... ... ... 420 0 0 One engineer ... --. ••• ••• • •• ••• 250 0 0 One assistant ... ... ... ... ••• ••• 200 0 0 Two men at £150 300 0 0 One man on race and line ... ... ... ... ••• 150 0 0 One man at Kuaotunu ... ... ... ••• ••• 150 0 0 Oil and sundries ... ... ... ••• •■■ ■•• 100 0 0 Total £3,407 11 10 It will be seen by this that I have added the extra men to that of Mr. Fletcher's estimate, as no doubt the water-race and line will take up the whole of one man's time to look after them; and as it will require three men to be in constant attention on the generating-plant at Gumtown, and one man at transformers, I think the estimate given not too high. The great difference between my estimate and Mr. Fletcher's is the cost of the water-supply ; and, at the time Mr. Fletcher left Wellington, I had not gone carefully into the matter, merely having mentioned to Mr. Fletcher that the cost of the open conduit would be about £1,000 per mile; but this would never cover the cost of fluming across the Eangihau, and raising the water out of the Eangihau and Waiwawa Eivers, where low concrete weirs would have to be placed, and closed boxing for a long distance down the side of these rivers, having piles driven to hold the boxing in position during time of floods. Assuming that the owners of the present crushing-plants had to pay the whole of the expense in connection with working the plant, taking into account interest on the outlay and depreciation of plant, it would amount to £681 10s. 4d. per annum for the owners of each of the five crushingbatteries that are at present erected at Kuaotunu. I have, &c, Henry A. Gordon, Assoc. M.lnst.C.E., The Hon. the Minister of Mines. Inspecting Engineer.

No. 2. Kuaotunu Scheme. —Mr. Fletcher's Eeport. A proposal to work the machinery for quartz-crushing and gold-saving in the Kuaotunu Field by power obtained and electrically transmitted from the Waiwawa and Eangihau Eivers. On the 9th May, 1893, accompanied by Mr. H. A. Gordon, Inspecting Engineer, visited Kuaotunu, where we were met by several of the mine-managers and others interested in the scheme. After discussing the subject with them, and visiting the Eed Mercury, Great Mercury, and Try Fluke Companies' works, we proceeded overland to Mercury Bay, and on the following day up the Whitianga and Waiwawa Streams to Gumtown, the place where the water motors and electric generators would be erected for transmitting the power to Kuaotunu. Following up the Waiwawa for about three miles to the site suggested for taking up the water, and selecting a suitable place above its junction with the Eangihau Eiver, we estimated from measurements of width, average depth, and velocity, the quantity of water then flowing to be 220-5 sluice-heads; adding 31 sluiceheads' (which we estimated from observation) to be flowing into the Waiwawa from the Eangihau, this gave a total of 251-5 heads of water. For the scheme to be satisfactory it is only the permanent effective power obtainable that must be considered, and to arrive at this it is necessary to estimate the probable minimum water-supply obtainable in an average dry season. The present year appears to have been an exceptionally wet one and although the river seemed to be pretty low at the time of our visit, yet from general indication's we deemed it advisable to largely discount the quantity of water which we estimated to be then flowing. From previous measurements made by Mr. Wilson, Inspector of Mines, when, after a period of two months' fine weather, he estimated that there were 144 sluice-heads, and from the opinions of others familiar with the district, we concluded (1) that at least one-quarter (say 63 heads) of the quantity flowing at the time of our visit would be available in an average dry season ; and (2) that probably one-third (84 heads) might be relied upon, unless there happened to be an exceptionally long spell of dry weather. To utilise this water and obtain sufficient fall it will be necessary to construct a race about five miles in length to bring the water into Gumtown, where a very suitable site for the necessary trans-mitting-plant can be obtained.

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The race, which would pass through open and suitable country, presents no great difficulties of construction, and, excepting at the intake, very little, if any, fluming would be required. As the banks of the Waiwawa are of a gravelly nature, it would be necessary to erect several chains of covered-in or box-fluming to lift the water out of the river. This fluming would have to be of a pretty solid construction to resist floods, and the large kauri-logs that might come down during a heavy fresh. The fall of the river from the proposed intake to Gumtown is about 90ft. ; thus, allowing 25ft. fall for race, and say 15ft. for rise of river in flood-time and clearance for turbine, an effective pressure of 50ft. could be obtained at the generator site. To bring the water from race to the turbines about 15 chains of 30-inch diameter iron piping would be required for each turbine. Allowing 70 per cent, efficiency for the turbines, the effective power obtainable at Gumtown for driving the electric generators would be, (1) 250-2-horse power, and (2) 332-9-horse power respectively. The distance from Gumtown to Kuaotunu in a direct line is about sixteen miles, but owing to unavoidable deviations that would have to be made, and the undulatory nature of the country, the power-line in all probability would be not less than twenty miles in length. By keeping well up the hill-sides a very suitable route could be obtained, and the bush almost if not entirely avoided. The whole route from Gumtown to Kuaotunu seems to be comparatively easy of access, so that the erection and maintenance of the present line would not be a serious undertaking. The next and perhaps most important question to be considered is the method of distributing the power at Kuaotunu. A considerable expenditure is necessary in the first place for the construction of a water-race to obtain power from the Waiwawa, there being no sudden fall in the river that could be used ; and the power obtained is not large, considering the distance it has to be transmitted and the purposes for which it is required. If the object of the scheme (the supply of cheap motive-power) is to be successfully accomplished, the most efficient and economical methods of distribution must be employed, or, in other words, the more the plant can be centralised at Kuaotunu the less will be the cost at which the power can be supplied. The existing battery-houses at Kuaotunu are all within a radius of about three-quarters of a mile, and the present number of stampers does not exceed fifty. There would be no great difficulty in establishing a crushing-plant on a site generally convenient for the existing mines; and then, if it was found that they could not employ all the available power, and the development of the field warranted it, a second crushing-plant might be erected at some other spot more centrally situated to the other mines that might then exist. As an alternative, each company could have its own electric motor at their works; but, unless the whole power were taken up by three or four companies, such a course could not be recommended, as a number of small electric motors would considerably complicate the scheme, decrease the efficiency of the plant, and add also to the first cost of installation, subsequent maintenance, and supervision. The method of transmitting the power to Kuaotunu, and distributing'it there, would be by what is known as the alternating current system. The electricity would be generated at Gumtown by alternating current dynamos, at a comparatively low pressure or electro-motive force, and then, by what are called "step-up" transformers, it would be converted or "transformed" into an electric current of high pressure (about 10,000 volts) but small quantity, before entering the line before transmission to Kuaotunu. At Kuaotunu the current would pass into a set of " step-down " transformers, which would transform it back again to a current of low electro-motive force or pressure, before being distributed to the electric motors. By the use of the alternative current system, the economy of light-pressure current transmission is combined with the convenience and safety of low-pressure generation and distribution—it being, in fact, the only practical means of transmitting large amounts of power to long distances.' The various losses that occur in the electric plant are here given:— No. 1. No. 2. Horse-power. Horse-power. Power given to electric generators ... ... ... 250-267 332-90 „ lost in electric generators ... ... ... 25-027 33-29 „ given to step-up transformers ... ... 225-24 299-61 „ lost in step-up transformers ... ... ... 11-262 14-98 „ given to line ... ... ... ... 213-978 284-629 „ lost in line ... ... ... ... 21-398 28-463 „ given to step-down transformers ... ... 192-58 256-166 „ lost in step-down transformers ... ... 9-629 12-808 „ given to electric motors ... ... ... 182-951 243-358 „ lost in electric motors ... ... ... 18-301 24-36 Effective or actual brake horse-power given out by electric motors ... ... ... ... 164-65 219-02 Percentage of power given by turbines, lost in generators and motor ... ... ... ... 17-30 Percentage of power given by turbines, lost in transformers ... ... ... ... ... 8-34 Percentage of power given by turbines, lost in line ... 8-55 Percentage of power given by turbines, given out by electric moters ... ... ... ... 65-78 99-97

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As previously mentioned, an efficiency of 70 per cent, has been assumed for the turbines; and, although higher efficiencies are declared by some of the manufacturers, it is doubtful if, in practice, any of them would be prepared to guarantee more than 70 per cent. An efficiency of 90 per cent, has been allowed in the foregoing calculations for the electric generators and motors, and 95 per cent, for the transformers. These efficiencies are below those claimed by the manufacturers, but may be relied upon if properly-designed apparatus suitable for the work is employed. Eecent careful and elaborate tests made in England of transformers of various makers gave efficiencies as high as 96-9 per cent., while all the best gave 95 per cent, and over. For driving the electric generators it would be desirable to use two turbines and horizontal shafts, each turbine being coupled direct to two electric generators, one at each end of its shaft. Such an arrangement, by avoiding the use of driving-belts or intermediate gearing, would be very compact and serviceable, economising power and saving wear and tear, also affording facilities for overhauls or repairs of turbines when such are necessary. Alternate current generators and motors possess considerable advantages with regard to the comparative ease with which repairs can be effected. The generating-coils are practically the only parts liable to damage ; but these are so subdivided, interchangeable, and easy of access, in welldesigned machines, that a workman of ordinary intelligence could replace an injured coil in a very short space of time, spare coils for the purpose being provided. In an installation of this nature, there is hardly any necessity to provide duplicate plant. The chances of a serious break-down are remote, while a temporary stoppage of a few minutes would not cause the inconvenience that might occur if the electricity was being used for lighting purposes. Having the plant in two units, by sections, further reduces the possibility of a total stoppage, so that hardly anything short of a collapse of the water-race or break-down of the power-line would produce such a result. If it was found, after the plant was installed, that the large amount of water (84 sluice-heads) could be depended upon, and that there was demand for such power, another turbine and electric generator could be erected, provision being made, in the first instance, in the design and arrangement of the plant, for possible future extensions. There would not be any particular advantage in commencing operations with less generating plant than that necessary for the minimum water-supply (63 sluiceheads) ; as, although there would be a saving in the first outlay in plant, the cost of water-race and power-line would be the same, and there wpuld be no reduction in the cost of attendance and general working-expenses. The estimate of cost of installation and annual working expenses here given is for the power delivered at Kuaotunu, and includes cost of electric motors and distributing apparatus. No allowance has been made for fixing motors, or adapting existing intermediate gearing at the various battery-houses, nor for connecting motors to distributing-station at Kuaotunu. This latter item will depend on the distance of the various companies' works from the station, and to some extent upon the amount of power they may require. The distance, in most cases, would not exceed one mile, but, as the companies would have to pay for the power lost in their connecting-wires, it would not be advisable to attempt to economise too much in the first outlay. At an average cost, about £70 to £80 per mile for poles, insulators, wires, and erecting, may be assumed. Fixing motors would cost very little, as they are compact and self-contained. Alterations to intermediate shafting to suit speed of motor, assuming that a steam-engine has been previously used, is the only other expense of installation. This would have to be considered for e_|ch particular case, but, probably, the cost of an extra pulley or two would meet requirements in most instances. The cost of waterrace has, upon Mr. Gordon's suggestion, been estimated at £1,000 per mile, including cost of fluming at intake. This price is, no doubt, on the safe side, but it is impossible to form a very correct estimate until the ground has been properly surveyed, and the route definitely fixed. With regard to labour, it will be noticed that provision has been made for four men, three of whom would be at the generating end, and one at Kuaotunu. With everything in good order there is hardly anything for the men to do at the generator-house beyond occasionally oiling the machinery and seeng that everything is working right. There are few moving parts in a turbine, or electricgenerator, and a turbine and generator would be coupled one to the other. The absence of belts, intermediate shafting, or gearing leaves very little to get out of order. Two men could do all that is required in the twenty-four hours, with two or three shifts, whichever might suit them best. The third man's duty would be to look after the water-race, and any other odd jobs that might arise. As the generating-station would be in a comparatively civilised locality—that is to say, there is a decent hotel and general store at Gumtown—it has not been considered necessary to provide house-room for the men, as they would, no doubt, make their own arrangements. It would be necessary to have a man stationed at Kuaotunu to look after the transformers and electric motors. One of the battery hands at each of the works, where the power was being used, could give such attention as the motor requires, during his shift, without interfering greatly with his ordinary duties; while the man, whose duty it was to see that the various motors were kept in good order, would always be within call, in case of any trouble arising, to set things aright again. Telephonic communications would exist between the various works using the power, and also between Kuaotunu and the generating-station. The items " Interest " and " Depreciation " speak for themselves, and require little comment. In an installation of this nature 5 per cent, is a very fair sum to allow for depreciation of the electrical and water plant. With regard to the water-race, there is very little to depreciate beyond a few chains of fluming that would be required. As provision has been made for a man to look after the race, and make such repairs as may be necessary from time to time, 2J per cent, is a fair allowance for material for making such repairs. It will be noted that the cost for break horse-power, delivered at Kuaotunu, works out at £13 18s. 4-J-d. per annum for 165-horse power, and £11 9s. 3'6d. for 219-horse power. This might have been expected; for, although the cost of plant is increased to provide the larger amount of power, the general and working charges do not increase in proportion. It is difficult to make comparisons between the cost here given per electrical break horse-power, if it may be so called, and an imaginary steam-

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engine of a class such as would be commonly used. Assuming that an engine of thirty or forty indicated horse-power could be made to work at 41b. of coal per indicated horse-power per hour each, allowing, say 15 per cent, extra for friction, the amount of coal per annum per break horsepower would be nearly 16J tons. This result is hardly likely to be obtained with the average engines and boilers met with in the mining districts; as, even with the best makers' engines it is only by using first-class coal, experienced engine-drivers, and working under most favourable conditions for a short time, that the economical results claimed by them is arrived at. Those who are most interested in the scheme can form the best opinion, by comparing figures here given with their monthly coal-bills, remembering that the power given out by the electric motors is effective, not nominal or indicated horse-power, and that it includes cost of motors. The result of such comparisons would be, no doubt, that they will find that steam-power costs them nearly three times the amount. The number of motors allowed for in the two estimates is five and seven respectively. Fewer motors, but of larger power, would be employed if the plant was contained in one large batteryhouse.

Estimated Cost of Plant, and Annual Working-expenses, to deliver 165 Brake Horse-power at Kuaotumt: Power electrically transmitted from Gumtown on the Waiwawa River. £ s. d. Water- and tail-race ... ... ... ... ... 5,000 0 0 Water-pipes ... ... ... ... ... ... 445 0 0 Turbines and fittings ... ... ... ... . . 500 0 0 House for turbines and generators ... ... ... ... 250 0 0 House for transformers at Kuaotunu... ... ... ... 100 0 0 Electrical apparatus, poles, insulators and wires ... ... 6,553 0 0 Packing, freight, insurance, and general shipping-charges ... 573 15 0 Freight and cartage from Auckland, 90 tons, at 20s. ... ... 90 0 0 Erecting-pipes, turbines, generators, transformers, and power-line 375 0 0 Supervision ... ... ... ' ... ... ... 300 0 0 Sundries ... ... ... ... ... ... 100 0 0 £14,286 15 0 Yearly Cost. =i^=ii===is £ s. d. Interest, 6 per cent, on £14,286 15s. ... ... ... 857 3 8 Depreciation, 5 per cent, on £9,286 15s. ... ... ... 464 6 9 Depreciation, 2-J- per cent, on £5,000 ... ... ... 125 0 0 One engineer ... ... ... ... ... ... 250 0 0 One assistant ... ... ... ... ... ... 200 0 0 Two men at £15 per cent. ... ... ... ... ... 300 0 0 Oil and sundries ... ... ... ... ... ... 100 0 0 £2,296 10 5 Annual cost per brake horse-power at Kuaotunu, £13 18s. 4^d. Estimated Cost of Plant, and Annual Working-expenses, to deliver 219 Break Horse-power electrically transmitted from Gumtown, on the Waiwawa River. £ s. d. Water-and tail-race ... ... ... ... ... 5,000 0 0 Water-pipes ... ... ... ... . . ... 650 5 0 Turbines and fittings ... ... ... ... ... 700 0 0 House for turbines and generators ... ... ... ... 300 0 0 House for transformers at Kuaotunu ... ... ... ... 100 0 0 Electrical apparatus, poles, insulators, and wires ... ... 7,311 17 0 Packing, freight, insurance, and general shipping-charges ... 686 13 0 Freight and cartage from Auckland ... ... ... ... 100 0 0 Erecting pipes, turbines, generators, transformers, and power-line 450 0 9 Supervision ... .. ... ... ... ... 300 0 0 Sundries ... ... ... ... ... ... ... 100 0 0 £15,698 10 0 Yearly Cost. £ s. d. Interest, 6 per cent, on £15,698 10s. ... ... ... 951 0 0 Depreciation, 5 per cent, on £10,698 ... ... ... ... 534 18 0 Depreciation, 2-| per cent, on £5,000 ... ... ... 125 0 0 One engineer ... ... ... ... ... ... 250 0 0 One assistant ... ... .. ... ... ... 200 0 0 Two men at £150 ... ... ... ... ... ... 300 0 0 Oil and sundries ... ... ... ... ... ... 150 0 0 £2,510 18 0 Annual cost per brake horse-power at Kuaotunu, £11 9s. 3-6 d. E. E. Fletcher.

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No. 3. Mr. H. A. Gordon, F.G.S., Inspecting Engineer, to the Hon. E. J. Seddon, Minister of Mines. Mines Department, Wellington, 21st July, 1893. Sir, — Ec Electrical Plant, Thames. In accordance with your instructions to visit and report, in conjunction with Mr. Fletcher, on the practicability of getting water as motive-power to generate electricity to work either crushingbatteries or a pumping-plant at the Thames, I have the honour to report as follows : — Before reporting on this work, I arranged with Mr. Fletcher to report on the practicability of getting water as a motive-power to generate electricity, also on the power required to be transmitted to the Thames to work machinery for pumping the deep levels; and he was to report on the electrical plant and the cost of the same. From the information previously received from the County Chairman, and those interested in the mining at the Thames, the principal object of our visit was to ascertain whether an electrical plant could be got to do the pumping at the deep levels at the Thames, and whether water could be got as a motive-power to generate the electricity. It was represented to me that there was abundance of water at the Billy-goat Falls, up the Kauaeranga Eiver, to give the required power. The County Chairman had previously some communication with Mr. Orchiston, Inspector of Telegraphs, who was erecting a telephone line from the Thames to the head of the County Waterrace. He recommended the construction of a dam across the Kauaeranga Stream, near the hotel in the Kauaeranga Valley, at a point high enough to supply the County Water-race with water, so that the upper portion of this race could be dispensed with, wid thereby lessen the cost of repairs. The scheme, therefore, that we were to examine and report on were : the practicability of getting a sufficient quantity of water at a high elevation near the head of the Kauaeranga Eiver to generate electricity to transmit sufficient power to the Thames to pump the deep levels; and also to report on the practicability of construction of a reservoir across the Kauaeranga Eiver at the hotel referred to, so as to get sufficient water and fall at this point for the required power. The first thing to consider is the power required to pump the deep levels ; and the only thing to guide one in this respect is the quantity of water there is to lift at the 500 ft. and the 640 ft. levels. The present pump is 24in. in diameter, and has to be worked from to 3f strokes per minute. The stroke is Bft., and, from all the information that I could obtain in the district, when this pump is working at the 640 ft. level, it takes about five strokes per minute to keep the water down. The quantity of water lifted would, therefore, be : 0-034 x 24 2 x 8 x 5 = 0-034 x 576 x 40 = 783 gallons per minute. It was stated that the water did not seem to increase from the 560 ft. level to the 640 ft.; but, be that as it may, there is a great possibility of more water being got at the deeper levels, and, therefore, provision should be made to cope with it in the event of it being struck. The depth of the shaft spoken of to test the deep levels is from 1,500 ft. to 2,000 ft. If the former distance be taken, and, say, that the quantity of water to be lifted is 800 gallons per minute, then the power required to lift this from a depth of 1,500 ft. would be: 33 000 "' = —33 — = 367 theoretical horse-power, to which should be added four-tenths for friction, 367 + 147 = 514---horse power; but if the shaft had to be sunk to a depth of 2,000 ft., then the power would be: -QQQQ ' = ——go — = 485 theoretical horse-power, to which must be added four-tenths; then 485 + 194 = 679-horse power would be required. The diameter of pumps to lift this quantity of water, say that two pumps were being used, the stroke being 7ft. and six strokes per minute, would be 0034 x7Y6 = 16'73plus a quarter the area : this shows that it would require two pumps, 18fin. in diameter; but in point of fact it would require two pumps, 20in. in diameter, to insure sufficient provision to cope with the water. The next question is the quantity of water available in the Kauaeranga Eiver that can be applied as motive-power without interfering with the present supply of water for the County Waterrace ; and in dealing with this question I will first take the scheme propounded by Mr. Orchiston, of the Telegraph Department, namely —a dam across the Kauaeranga Eiver, at the Kauaeranga Valley Hotel. According to the barometer levels, the water-race crossing in front of the door of the hotel referred to is about 72ft. above the level of the river at this point, and the bed of the river is about 90ft. above high-water mark. To raise the water from this river it would be necessary to construct a concrete weir ; the height of which would be 74ft., and the distance across at the top would be about 15 chains. There is always a quantity of kauri-logs coming down this river when it is in flood, and these going over the top of a weir of the height mentioned would very soon break up the concrete at the toe of slope of the wall, and be a continual source of expense in keeping it in repair. It was suggested by Mr. Orchiston that a fence could be put on the top of the weir to stop the logs from going over, and that a sluice could be made at one side to let the logs go down the creek; but this would interfere with a continuous supply of water, as when the sluice-gates were opened to allow the logs to go down, the water would be below both the present race-level, and also below the level of the race that would require to be constructed to work the water motors. This reservoir would back the water for about two and a half miles up the valley, and therefore cover a considerable area of private property, for which compensation would have to be paid, and this in itself would amount to a considerable sum; still it would be but a mere mite to the cost of construction of a weir across the river-bed, and the great height of this weir would necessitate a water cushion being made at the back, which would add considerably to the quantity of concrete required. It would be impossible to give anything like a correct estimate of the cost of this work without a survey being made, and the depth of foundations ascertained, but in all probability it woidd be about £76,000; and probably between compensation for land, and cost of constructing a

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water-race, with fluming, iron pipes, and water-motors, it would amount to £86,000; but irrespective of the cost I would not recommend so high a weir as this to be constructed, as the risk of damage in time of floods is too great when hundreds of kauri-logs are coming down the river. After examining the river at this point, it was suggested that a weir 50ft. in height across the bed of the Kauaeranga Eiver would be sufficient, but, seeing that this river sometimes rises to a vertical height of 10ft. and 12ft. in times of flood, bringing down hundreds of kauri-logs, necessitating a large expenditure in its construction, without giving a compensating benefit. Wherever high weirs are constructed in rivers, unless they are made remarkably strong, they are always liable to be damaged in times of high floods ; and in the case of a weir 50ft. high in the Kauaeranga Eiver, the kauri-logs coming down would considerably increase the liability to damage. The reason given for a dam at this particular place is, that there is a large branch creek joining the Kauaeranga Eiver between this point and the head of the County Water-race, in which there is said to be always a large supply. At the place where the County race lifts the water from there is always a considerable quantity going down the river-bed amongst the shingle; the head of the race is merely taken into a water-hole, and no provision made to stop the water from getting through the shingle. If a concrete wall were placed across the river at this point there would always be a plentiful supply of water even in dry seasons. It is possible that there might be such a thing as thirty sluice-heads going over this weir if constructed near the Kauaeranga Valley Hotel in dry seasons, but in ordinary weather there would be a very large supply. However, as it is for motive-power for pumping, an intermittent supply of water would be of little use, therefore the minimum quantity should only be taken. Taking all the available head that could be got, after deducting the fall for the water-race to convey the water down to near high-water mark, it would not , , . ,-, , , 140 x6O x 62-5 x3O .„ ~ ~ , , ~, exceed 140 ft., and this would only be 33000 = 478 theoretical horse-power ; and the water-motor would only give about 70 per cent, of this, or 334-6-horse power, for generating the electricity, therefore, deducting the percentage of the power lost in the dynamos and motors, as well as in transmission on the line, there would not be sufficient power to be of much use to pump the deep levels. In regard to taking the water from the Billy-goat Falls : these falls are situated in a branch creek joining the Kauaeranga Eiver, about 15 miles up from Parawai. The bed of the river at this point is 800 ft. above sea-level, and the top of the Billy-goat Falls is about 1,300 ft., therefore the falls are about 500 ft. in height; but there would be very little water coming over them in dry seasons, possibly not more than two- sluice-heads. There are other falls about four miles up the Kauaeranga Eiver, with about the same quantity of water in dry seasons, and they are said to be about the "same height; but we did not go up to them, as we would not have been able to return the same night to the Thames, and there was no place of accommodation to stop at. The Billy-goat Falls would give, with two sluice-heads of water, 113 theoretical horse-power, which would not be sufficient to put up au electrical plant for the transmission of power, the distance being nearly 20 miles. The only way of getting power from the Kauaeranga Eiver would be to construct a water-race from the falls up the Kauaeranga Eiver, and pick up the different branches of the river on the north side, returning the water into the river at the head of the County Water-race. By this about twenty sluice-heads of water could be lifted in dry weather, and there would be an elevation at the terminating point of the water-race of about 350 ft. This would give as follows: 20 x 62-5 x 60 x 375 _ 75 x 375 _ 852 theoretical horse-power, and to take 70 per cent, of this, it 33,000 3o gives 596-horse power available for driving the dynamos. In regard to the cost of the latter proposition, it would be difficult to give an approximate estimate without a survey. The country appears very broken in places, and, unless the line of conduit were actually traversed, one could form no idea whether an open conduit could be constructed for the whole of the distance, or whether fluming would be required. Judging from the character of the country, a contour line would be about 10 miles in length ; but if the work of prospecting the deep levels was decided on, this scheme should be further investigated. I think it possible that if a water-race were actually surveyed, there might be an available head of 400 ft., and that would give 909 theoretical horse-power; the water motor giving 70 percent, of this, 696---horse power would be available to generate the electricity. On the supposition that 60 per cent, of this can be transmitted as available power to work machinery, 357-6-horse power would be available, and the expense of working this would be about £35 per week, exclusive of the interest on capital, and sinking fund for depreciation. Any scheme for getting a large amount of power from the Kauaeranga Eiver will entail works of considerable magnitude ; and, on a cursory view of the ground, the same as Mr. Fletcher and myself had, it would be presumption on our part to give anything purporting to be a clear approximate estimate of the cost; surveys, levels, and cross-sections would have to be taken before arriving at anything reliable. I have, &c, Henry A. Gordon, Assoc. M.lnst.C.E., The Hon. the Minister of Mines. Inspecting Engineer.

No. 4. Thames Scheme. —Mr. Fletcher's Eeport. A proposal to obtain power from the Billy-goat Falls, at the head of the Kauaeranga Valley, and from the Kauaeranga Eiver, for mining purposes at the Thames. On the 16th May, 1893, in company with Mr. Gordon, Inspecting Engineer, I visited the Billygoat Falls, at the head of the Kauaeranga Valley here. Although a magnificent fall as far as height

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is concerned we found very little water, there being not more than three sluice-heads coming down the creek at the foot of the falls. This quantity in dry weather would, no doubt, dwindle away to practically nothing, so that it could not be depended upon as a source of permanent power. Mr. Park, of the School of Mines, and Mr Orchiston, Inspector of Telegraphs, who accompanied us, scrambled up to the top of the falls, and found the height, as shown by an aneroid barometer, to be 825 ft. from base to top. The country round about is covered with dense bush, so that even if there was power here it would entail a considerable expenditure to clear a route for the power-line, and make a track sufficiently good to get up the apparatus. For any mine requiring power in the immediate neighbourhood this fall might be of use, as one sluice-head of water would give fully 65-horse power. Another suggestion was to construct a dam or weir across the Kauaeranga, a few miles above Grahamstown, where the river is narrowed down considerably by rocky bluffs on each bank, forming natural buttresses against which the dam or weir could be built. It was considered that it might be practicable to make the dam the height of the Thames County Water-race, which passes close by, and by forming a huge reservoir, insure a constant supply of water to the race as well as creating a source of power that might be electrically transmitted to Grahamstown and neighbourhood. The height of the race above the river-bed was found at this point to be about 71ft., so that the construction of a dam of this height was practically out of the question on account of tiie enormous outlay necessary. We then considered a suggestion to construct a weir 50ft. in height, and then by means of a water-race, three or four miles in length, to increase the fall to about 100 ft. It might be possible to obtain a constant supply of water of about 100 sluice-heads, as the weir would dam back the river for about a mile or a mile and a half, thus forming a very large storage area. This quantity of water would give about 790-horse power to be electrically transmitted to Grahamstown, where it could be used for working the big pump. Assuming that about 550-horse power was given out by the motors at Grahamstown, which is allowing 70 per cent, efficiency, it is questionable whether electricity could compete in this case with modern steam pumping-machinery, owing to the very heavy expenditure necessary for construction of weir and water-race. Mr. Gordon's rough estimate for weir and race was £86,500, to which must be added about £14,000 for pipes, turbines, buildings, and electrical plant, &c. This would represent a capital outlay of, say, £100,000. The annual expenses would be probably as follows:— £ Interest at 6 per cent, on £100,000 ... ... ... ... 6,000 Depreciation, 2J per cent, on £86,000 ... ... ... ... 2,150 Depreciation, 5 per cent, on £14,000 ... ... ... ... 700 Engineer and assistants ... ... ... ... ... ... 750 Oil and sundries ... ... ... ... ... ... 150 £9,750 The annual cost per brake horse-power on the above expenditure amounts to £17 14s. 6|d. E. E. Fletcher. Approximate Cost of Paper.— Preparation, not given; printing (1,575 copies), £6 10s.

Authority: Samuel Costall, Government Printer, Wellington.—lB93.

Price, 6d.]

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