D. VAJV JSrOSTIiAJVD. 23 



Mitchell's Manual of Assaying. 



8vo. Cloth. $10.00. 



A MANUAL OF PEACTICAL ASSAYING. By Jonif Mitchell. 

 Third edition. Edited by William Ckookes, P.E.S. 



In this edition are incorporated all the late important discoveries in Assay- 

 ing made in this country and abroad, and special care is devoted to the very 

 important Volumetric and Colorimetric Assays, as well as to the Blow-Pipe 

 Assays. 



Benet's Ohronoscope. 



Second Edition. 



Illustrated. 4to. Cloth. $3.00. 



ELECTEO-BALLISTIO MACHINES, and the Schnltz Chrono- 

 scope. By Lieutenant-Colonel S. V. B£N£i, Captain of Ordnance, 

 TJ. S. Army. 



Contents.— 1. Ballistic Pendulum. 2. Gun Pendulum. 3. Use of Elec- 

 tricity. 4. Navez' Machine. 5. Vignotti's Machine, with Plates. B.Benton's 

 Electro-Ballistic Pendulum, with Plates. 7. Leur's Tro-Pendulum Machine 

 8. Schultz's Chronoscope, with two Plates. 



Michaelis' Chronograph. 



4to. Illustrated. Cloth. $3.00. 



THE LE BOULENG^ CHRONOGEAPH. With three litho- 

 graphed folding plates of illustrations. By Brevet Captain E. 

 Michaelis, First Lieutenant Ordnance Corps, U. S. Army. 



" The excellent monograph of Captain Michaelis enters minutely into the 

 details of construction and management, and gives tables of the times of flight 

 calculated upon a given fall of the chronometer for all distances. Captain 

 Michaelis has done good service in presenting this work to his brother ofSoers, 

 describing, as it does, an instrument which bids fair to be in constant use in 

 our future ballistic experiments.' — Arm^ and Navy Jowmoi^ 



