denser per gauge, 27 inches. When this diagram was taken, the vessel was very light.

The cut-off used was Sickle's arrangement, as originally patented; that is, the valve was tripped from the lifting rod. The diagram shows the steam valve to have had no lead; the exhaust valve did not open until the steam stroke was entirely performed, and it seated before the exhaust stroke was completed, cushioning the steam at A.

The space between the valves and in the cylinder nozzle added to the clearance make 2.6 cubic feet to be filled with steam before each stroke can be commenced: this steam is not entirely lost when the engine works expansively; it would be entirely lost did the steam follow for the full stroke; and this loss will become less and less in proportion as the steam is worked more and more expansively. In the present case of the "Michigan," 2.6 cubic feet is equivalent to 0.368 foot on the length of the cylinder. The mean effective pressure in the cylinder for the whole stroke of 8 feet being 18:44 lbs. per square inch; the total power developed by the engine can be represented by 18-44 x 8=147.52. The effective pressure at the end of the stroke (at which pressure the exhaustion takes place) is 8.5 lbs.; consequently the power lost by filling the vacuities before the stroke commences, can be represented proportionally by 8.5 x 0.368-3-128, and 3.128 is 2.12 per cent. of the total power, 147-52; therefore, 2-12 per cent. of the total power developed by the engine has been thus lost.

Indicator Diagram from the Steam Cylinder.-Steam pressure in boiler per gauge, 15.5 lbs. per square inch. Vacuum in condenser per gauge, 27 inches. Strokes of piston per minute, 36. Vessel very light. Mean effective pressure 14.4 lbs. per square inch. Area of valve opening 121.66 square inches. Capacity of cylinder, 56.544 cubic feet. Indicator Diagram from Air Pump.-Temperature in air pump, 100° Fahr. Mean effective pressure, 6.625 lbs. per square inch. Capacity of air pump, 12 cubic feet. Capacity of condenser, 21 cubic feet.

Railway Traffic.*

The railway traffic for the past year presents a gratifying resultwe mean as to the increased amount of it. Increased profits are another matter, dependent in a principal degree on the capital accounts remaining stationary, or nearly so, which unhappily has not by any means been the case. Well, the traffic of 1850 has exceeded that of the former year by no less a sum than 1,741,418. The traffic of the past year (1850) reached the figure of 13,142,235l., and is derived from 6733 miles of railway, including those comparatively few Companies, old and new, who do not publish their returns in the regular way, but who cannot nevertheless evade a knowledge of the true amount of their traffic, or a very near approximation to it. This gives an average receipt per mile per annum of 1944/.

But if we confine ourselves to the amount of traffic as furnished by the publishing or above-board Companies, rejecting that of those who withhold their traffic returns, we find the receipt per mile per annum ranging higher, simply because it is only the very inferior lines which avoid publication; the lines with very mean traffics. The average then rises to 22271. per

From the London Railway Journal, No. 605.

mile per annum. The traffic of the publishing Companies amounts, during the last year, to 12,755,235l.; the miles open at the end of the year were 6257. But we must not, of course, divide the receipt of 12,755,2351. by the miles then open (6257) to get at the receipts per mile per week. That would be very fallacious. For the 6257 miles were not open during the whole of the year. On the contrary, at the beginning of the year, only 5256 miles were open, or about 1000 miles less. The mileage went on increasing week after week, and month after month, until it reached, at the end of the year (in respect to the publishing Companies) the extent of 6257 miles. We get at the year's average per mile by adding up the week's averages per mile, a method by which truth, as near as it is possible to reach it, is arrived at. We may then say that the average mileage receipt per annum of all the publishing Companies was, for 1850, 22277. And it is useful to make this separation of the publishing Companies from the hole-and-corner ones for the sake of comparison with past years, for which we could not possibly make any estimate of the secret Companies' traffic.

In comparison with former years the traffic per mile per annum stands thus:

Observe how the traffic increased per mile from the year 1842 until 1845, when it reached its maximum. And then from 1845 to the last year, how it sank down, like the mercury in bad weather, to the very lowest point it has yet reached, viz., 22271. But it is satisfactory to notice that the difference between the last year's traffic and that of the former ones is much less, notwithstanding that we have had a greater number of miles opened in 1850 than in any one of the former years. For, during the year 1843 there were 56 miles opened; during 1844, there were 194 miles opened; during 1845, there were 263 miles opened; during 1846, 593 miles; during 1847, 839 miles; during 1848, 975 miles; during 1849, 835 miles; and during 1850, more than 1000 miles. We must, however, here remark that, although there were for the purposes of this table more than 1000 miles opened during the past year (1850,) yet, in point of fact, only 591 were opened during that year. The additional four or five hundred miles were in reality opened during former years, but in pursuance of that narrow-minded policy which demeans a good deal of railway management, the Companies opening those four or five hundred miles did not immediately publish the traffic returns of them, because forsooth, they (the directors) wished to have a short time to themselves for the traffic to develope itself; fearing that the "public" should be alarmed" by what they called a " premature" publication, albeit the public, that is, the Shareholders, took much greater alarm by being kept in the dark, and did not at all relish the circumstance of the Directorates keeping the information as to how the traffic was getting on, entirely to themselves.

There is now every probability of the mileage traffic not only ceasing to decrease, but to begin again to take an upward tendency. But really and truly, it depends much upon whether the Directors and Shareholders

will be prudent. If they resolve to make for the present as few more miles as possible, then we cannot doubt that the mileage receipts would soon tend upwards, and, as a consequence, the dividends increase. Suppose for the sake of argument, that the mileage now stopped at what it is, and the capital accounts were closed, does any one think the traffic per mile would not go on increasing? So extremely sudden and decisive a step we know will not be taken. The lines three-parts finished must be completed. The present mileage must be further increased to some extent. In that there is no danger. The danger is, that Directors and Shareholders will not be true to their own interests; or that Directors will go mad again, and Shareholders renew their foolish and almost criminal state of indifference; that between them they will rush again into the wildest speculation, or not now close up as quickly as they can. If Directors will do their duty, which we think we are fully warranted in saying they certainly will not, unless the Shareholders look well after them, there is little fear that in course of time railway matters will be righted. The traffic of this year is expected to do something material in rectification of them.

The 6733 miles, including those "little goes" who sink into the back ground, and do all they can to avoid publication, have cost the enormous sum of 230,522,731., being at the rate of 34,2381. per mile.

The closing of the capital accounts, that is the great object at which the Shareholders should strive; and yet it is the very one which we were jeered at for being the first to moot. We wanted the capital accounts for the old lines closed at once, and those for the new closed as soon as possible. For, just see how the keeping of them open works. Shareholders have vainly flattered themselves with the belief that the new and cheaper railways were bringing down their average mileage cost. No such thing. Instead of that, the average mileage cost has been going up. In 1842 the cost per mile was 34,690.; in 1843, 36,360l.; in 1844, 35,670.; in 1845, 35,070l.; in 1846, 31,860.; in 1847, 31,7097.; in 1848, 34,2347.; in 1849, 35,2147.; and in 1850, 35,2291. So that notwithstanding all the new and cheaper lines, it is actually now higher than in 1842. And it will go on increasing if Shareholders do not go on supervising. The "IMPROVEMENTS" of the lines will never cease as long as Shareholders are simple enough to pay for them, or subscribe large sums of money without knowing to what they are applied.

With good management there is great hope, and trusting that means will be taken to obtain it where it is wanting, and keep it where it is found-and determined to do our part towards railways-we think we might wish our readers a happy new year.

New Method of Preventing Incrustations in Steam-Boilers.*

Mode of preparation, by M. Saillard, of Nantes:-Catechu, 100 lbs.; subcarbonate of potash, 50 lbs.; subcarbonate of soda, 50 lbs.; common resin, 10 lbs.; lime, 20 lbs.; water, 300 lbs.-1. Boil for 20 minutes the subcarbonate of potash and soda with the lime and resin, with 200 parts of water; remove the fire, allow the mixture to settle, and draw off the clear liquor.-2. In another boiler, make a decoction of the catechu, in

From the London Mining Journal, No. 802.