wall of the house by means of 13 supports placed at equal distances from the base to the summit (as shown in Fig. 2).  When the gasholder is perfectly empty, the three lifts are inclosed, one in the other, and rest with their lower edges upon the bottom of the tank.  In this case the roof of the top lift rests upon a wooden framework.  Fixed in the floor of the tank are 144 posts, 9 inches thick at the bottom and 6 inches thick at the top, to support the crown of the holder in such a way that the tops are fixed in a kind of socket, each of them being provided with four horizontal bars, which decrease in thickness from 305 by 100 mm. to 150 by 50 mm., and represent 16 parallel polygons, which in their turn are fastened diagonally by means of iron rails 63 by 100 mm. thick, arranged crosswise.  The top of this framework is perfectly contiguous with the inside of the crown of the gasholder.  The crown itself is made up of iron plates, the outer rows having a thickness of 11 mm., decreasing to 5 mm. toward the middle, and to 3 mm. at the top.  The plates used for the side sheets of the holder are:  For the top and bottom rows, 6.4 mm.; and for the other plates, 2.6 mm.

* * * * *

A new bleaching compound has been discovered, consisting of three parts by measure of mustard-seed oil, four of melted paraffin, three of caustic soda 20 deg.  Baume, well mixed to form a soapy compound.  Of this one part of weight and two of pure tallow soap are mixed, and of this mixture one ounce for each gallon of water is used for the bleaching bath, and one ounce caustic soda 20 deg.  Baume for each gallon is added, when the bath is heated in a close vessel, the goods entered, and boiled till sufficiently bleached.

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GEORGE W. WHISTLER, C.E.

[Footnote:  A paper by Prof.  G.L.  Vose, Member of the Boston Society of Civil Engineers.  Read September 15, 1886.]

By Prof.  G.L.  Vose.

Few persons, even among those best acquainted with our modern railroad system, are aware of the early struggles of the men to whose foresight, energy, and skill the new mode of transportation owes its introduction into this country.  The railroad problem in the United States was quite a different one from that in Europe.  Had we simply copied the railways of England, we should have ruined the system at the outset, for this country.  In England, where the railroad had its origin, money was plenty, the land was densely populated, and the demand for rapid and cheap transportation already existed.  A great many short lines connecting the great centers of industry were required, and for the construction of such in the most substantial manner the money was easily obtained.  In America, on the contrary, a land of enormous extent, almost entirely undeveloped, but of great possibilities, lines of hundreds and even thousands of miles in extent were to be made, to connect cities as yet unborn, and accommodate a future traffic of which no one could possibly foresee the amount.  Money was scarce, and in many districts the natural obstacles to be overcome were infinitely greater than any which had presented themselves to European engineers.