D. VAN NOSTRAND. 3 
"Williams on’s Meteorological Tables. 
4to. Flexible Cloth. $2.50. 
PEAOTICAL TABLES IN METEOROLOGY AND HYPSO- 
METRY, in connection with the use of the Barometer. By Col. 
R. S. Williamsox, U. S. A. 
Merrill’s Iron Truss Bridges. 
Third Edition. 
4to. Cloth. $5.00. 
IRON TRUSS BRIDGES FOR RAILROADS. The Method of 
Calculating Strains in Trusses, with a oareful comparison of the 
most prominent Trusses, in reference to economy in combination, 
etc., etc. By Brevet Colonel William E. Merrill, U.S.A., 
Major Corps of Engineers. Nine lithographed plates of illustra- 
tions. 
“ The work before us is an attempt to give a basis for sound reform in this 
feature of railroad engineering, by throwing ‘additional light upon the 
method of calculating the maxima strains that can come upon any part of a 
bridge truss, and upon the manner of proportioning each part, so that it shall 
be as strong relatively to its own strains as any other part, and so that the 
entire bridge may be strong enough to sustain several times as great strains 
as the greatest that can come upon it in actual use.’ ”—Scientific American. 
“ The author has presented his views in a clear and intelligent manner, and 
the ingenuity displayed in coloring the figures so as to present certain facts 
to the eye forms no inappreciable part of the merits of the work. The reduc- 
tion of the ‘ formuks for obtaining the strength, volume, and weight of a cast- 
iron pillar under a strain of compression,’ will be very acceptable to those who 
have occasion hereafter to m'ake investigations involving these conditions. As 
a whole, the work has been well done.”—Snüroad Gazette, Chicago. 
Allan’s Theory of Arches. 
18mo. Boards. 50 cts. 
THEORY OF ARCHES. By Prof. W. Allax, formerly of 
Washington and Lee University. Illustrated. 
“ This little volume is an amplification and explanation of Prof. Rankine’s 
chapters on this subject.”