SCIENTIFIC NOTES.

Press, Volume XIX, Issue 2811, 6 May 1872, Page 3

SCIENTIFIC NOTES.

The London correspondent of the Australasian writes as follows :— It is a singular fact that, after all these years of railway experience, we should be, apparently, only learning now what are the most economical principles both of construction aud working. Since the opening of the Manchester and Liverpool line in 1820 nearly forty-three years have elapsed, during which time railway activity has been ceaseless, and millions of money have been poured forth like water. But only at the present time do we appear to be really and thoroughly impressed with the notion that half our money has been wasted from cumbrousness of scale, while only half our resources of railway use have been developed. I am led to make these remarks after hearing what a Fairlie double-bogie locomotive was made to do the other day on a steep and windiug mineral line near Sheffield, which was two miles long, had two chief gradients—l in 50 for 1880 yards, and, 1 in 32 for 396 yards— aud had curves co numerous and sharp that they represented the figure of the letter S. No engine has ever been able to take np above nine trucks at a time, the whole weight of the train (with engine) being 145 tons, of which only 32 would be of any use in increasing the adhesion of the coupled wheels. The great beauty of the Fairlie engine, though it weighs more by seven ton's than the ordinary locomotive and tender, is, that it is pivoted-upon two" six-wheel platforms, upon which the coal and water are placed, so that the whole weight is available for adhesion, as the tender (about 16 tons) is dispensed with as \\h profitable. The train included 17 waggons, loaded with iron and coal, and weighing (with the engine) 300 tons—more than double the load usually worked with. Fearful lest the coupling irons should anap with the strain, the engineers first of all placed the Fairlie at the tail of the train to push, which it did with such good will that it rattled up an ascent of 1 in 50 without any diminution of speed. In the middle of the abruptest curve, and on a gradient of 1 in 30. the engine was easily stopped, and returned steadily down hill, bringing the train after it. In the next experiment there were five trucks added, making altogether twenty-four, of the weight of 360 tons ; and notwithstanding this enormous load, the train again ran up the ascent, stopped at the same gradient, started again (though with some difficulty), and soon got up a speed of ten miles an hour. We have never had the powers of a Fairlie engine demonstrated so conclusively as this, and all colonial eoyaeess should seriously consider The mutter before laying out new lines. One of the great difficulties of railwaymaking seems to lie in the permanent way, which is often as complicated in its arrangement as it should be of simple character. Mr Griffin, an English engineer, has bro.ugfct out a very excellent permanent way, which appears tounitesimpljetsy, safety, and economy. It would ba uninteresting to my readers to describe the technicality of it, but I may briefly specify the advantages, which are— that 'the height of the rail from the base of the sleeper is very much less than usual, thus decreasing the leverage prodaced on the parts by the motion of passiDg trains. The comparatively elastic bed given to the rail enables it to be turned when the top face is

worn away, whereas by the usual System the bottom face becomes so indented th.it it is j never fit for turning. .' uch 11 .• t rail, too, can be used, caus: ' --. c.xrr.ix.- ia the material. sleepers of loss size may be laid ; and as regards repairs. any sleeper can be replaced by simply removing the ballast from around it and withdrawing one bolt. If our railways are to pay, they must be laid as cheaply as j possible consistently with strength and duration ; and Griffin's permanent way eei'ainly i seems to solve the question to a great extent. The cause of the fracture of railway wheel tires, by the way, si'th u> he definitely ascertained to arise in.:u excess of cold, as in the winter time in Prussia from 200 to SOO tires brer.k, varying with the temperature of the weather ; and experiments were tolerably conclusive that axles made of the same cast steel behaved differently at different temperatures. One tire which was exposed to the frost broke at, the first blow of a falling weight, while another, which had been kept in the warm shop, bore 3t> of the same blows before breaking. Of course, the character of the iron has something to do with it. especially when there is too little phosphorus ; but cold appears to be the ruling cause. I perceive that in Canada wooden railways are coming into vogue, on the gauge of 4ft The rails are made of maple, and are 14ft in length, the ties being of hemlock and tamarac, which are brought down from the woods through which the line runs, put on a trolley and taken to a circular saw, where at one operation they are mortised as required. The cost of the whole line and rolling stock is only 5000 dollars per mile, and the trains run with great smoothness at the rate of twentyfive miles an hour. As far as expense goes, the wooden rail is worth trying, but I should doubt its lasting powers ; and if tried in tropical country, I should not be surprised if ants made a clean sweep of the whole concern. For an agricultural district, however, the last and best new thing is said to be a railway called, after the inventor, " Corbin's Universal Carrier." which is very simple, and very cheap. It consists, in fact, of a portable tramway of wooden frames, formed by two longitudinal balks of timber, divided into bays by crossties. Upon the longitudinal trucks is placed a very flat and thin rail— et voila totitl When the rails are wauted to be laid—say in a sugar or beetoot plantation—all that is to be done is to lay the rails on the ground following the undulators, and joint them together by clip and some wooden trenails. The trains are simply a number of little trucks, or frames, with iron standards. The great recommendation of the system is not only its cheapness of construction, but that the power of traction, which on ordinary level ground amounts to 25 per cent, of the weight to be drawn, ia here reduced to less than 1 per cent, on level ground. By limiting the outside dimensions of the waggons, the pressure on the surface of the ground is correspondingly limited, and really but little more than one-third of a man walking— so that the tramway may be used in soft and boggy ground where a man would sink. M. Corbin (who is a French engineer) has also devised some waggons which are self-moving, each waggon being provided with two steam cylinders, which affect its own wheels, and is, in fact, a miniature locomotive.