40 SCIENTIFIC BOOKS PUBLISHED BY 



Saeltzer's Acoustics. 



12mo. Cloth. $2.00. 



TEEATISE ON ACOUSTICS in Connection with. Ventilation. 

 With a new theory based on an important discovery, of facilitat- 

 ing clear and intelligible sound in any building. By Alexakdek 

 Saeltzee. 



" A practical and very sound treatise on a subject of great importance to 

 architects, and one to -which there has hitherto been entirly too little attention 

 paid. The author's theory is, that, by bestowing proper care upon the point 

 of Acoustics, the requisite ventilation will be obtained, and vice versa. — 

 Brooklyn Union. 



Myer's Manual of Signals. 



New Edition. Enlarged. 



12mo. 48 Plates full Koan. $5.00. 



MANUAL OP SIGNALS, for the Use of Signal Officers in the 

 Field, and for Military and Naval Students, Military Schools, 

 etc. A new edition, enlarged and illustrated. By Brig. -Gen. 

 Albert J. Mteb, Chief Signal Officer of the Army, Colonel of 

 the Signal Corps during the War of the BebeUion. 



Larrabee's Secret Letter and 

 Telegraph Code. 



18mo. Cloth. $1.00. 



CIPHEE AND BECEET LETTEE AND TELEGEAPHIO 

 CODE, with Hogg's Improvements. The most perfect secret 

 Code ever invented or discovered. Impossible to read without 

 the Key. Invaluable for Secret, Military, Naval, and Diplo- 

 matic Service, as well as for Brokers, Bankers, and Merchemts. 

 By C. S. Laseabee, the original inventor of the scheme. 



