D.—s

2

This makes the average monthly expenditure to be £172 Is. Id., while the average monthly receipts only amount to £86 Bs. 6d. The following table will likewise show the number of claims that have been worked by the aid of the channel, the average number of days each worked, and the number of men employed :—

This shows the average number of men employed in claims using the sludge-channel during the first year that it has been in operation to be 74 nearly, and the average number of days in each month that each claim has used the channel for four hours each day to be 13J. It likewise shows the cost of maintenance to be about £12 15s. per day of four hours each, or about £1 per man per week for each man that was sluicing into the channel, whereas the charge for using the channel is only 10s. per man per week. The total cost of the sludge-channel up to the present time is about £17,200. Having now gone into the present receipts and expenditure, and shown clearly that the fees charged for the use of the channel are only one-half what it has cost to keep it in maintenance, the next question that presents itself is, can the cost of maintenance be lessened by adopting other systems of paving; or will the widening of the channel lessen the cost of the maintenance for the future ? The nature of the ground in the vicinity of Kumara, and generally on the West Coast, is entirely different from the ground in Otago, which is worked with extensive sludge-channels : in the latter place the material is of a fine nature and does not wear away the paving at nearly so rapid a rate; and the absence of large stones rolling down the channel makes the pavement far easier kept in position; therefore the same description of a sludge-channel that is used for working the ground in Otago would not be suitable for working the ground in the vicinity of Kumara. The most reliable information that can be got on the system of paving sluices is from the hydraulic workings in California, which are somewhat of a similar character to the workings about Kumara. There is a book recently published by Alfred G. Lock, F.8.G.5., entitled, " Gold: its Occurrence and Extraction," which gives valuable information on the subject of groundsluices, giving the fall required and the class of paving that is most economical, to use. It may not be out of place here to give some idea of the magnitude of some of the hydraulic operations that are carried on in California, showing the large amount of money that is spent by private enterprise in works of this nature. The following table will show the magnitude of some of the works:—

This author goes on to shoi# that the dimensions of a sluice in California are determined by the quality of the material to be treated, which is governed by the water-supply. One 6 feet wide and 3 feet deep, with a 4- to 5-per-cent. grade, will take 3,500 miners' inches of water which is equal to about 5,250 cubic feet of water per minute; one 4 feet wide and 2-J- feet deep, with 2-1-per-cent, grade, will take 1,200 to 1,500 miners' inches, equal to 1,800 to 2,250 cubic feet per minute ; or with 4-per-cent. grade, will take about 3,000 cubic feet of water per minute to work it. This infor-

Month. Number of Claims using the SludgeChannel. Number of Men employed in Claims using the SludgeChannel. Average Number of Days that each Claim has used the Sludge-Channel. .882—May ,, June July ,, August ,, September... ,, October ,, November ... ,, December ... .883—January ,, February ... ,, March ,, April 4 7 7 9 12 17 14 18 17 18 20 19 23 29 35 49 67 84 72 98 92 104 118 112 27 13 16 14 16 15 4 10 13 18 15 12 Totals 162 883 173

Name of Company. Length of Tunnel. Average Grade of Tunnel. Reported Cost. vTorth Bloomfield ... American French Corral 3ed Eock ?arrell ... Sweetland Creek ... tlanzanita 3oston ... English Mine Ft. 8,000 3,900 3,500 2,600 2,200 2,200 1,740 1,600 1,400 Ft. per 100. 6* 4§ «i 3* 4f 71 7 £ 100,000 28,000 33,000 18,000 12,000 8,000