L. MECHANICS AND ENGINEERING. 475 



combustible is said to be more than double that of coal ; so 

 that with 1000 pounds of the new material M. Pogliani 

 claims to have secured a result equal to that of 3000 pounds 

 of common coal. For this reason its use is urged for steam- 

 vessels, especially those which are obliged to remain a long- 

 time at sea without the means of renewing their supply. 

 3 B, November 6, 1873, 403. 



SYSTEM OF OPTICAL TELEGRAPHY. 



A system of optical telegraphy, somewhat like that de- 

 vised in France and Italy, has been announced by Mr. Gus- 

 tin, of Troy, who uses an instrument like a head-light to a 

 locomotive, with a shield that fits over and shuts off the 

 light. The operator sits behind, and an attachment, worked 

 by the hand, lifts the shield, throwing forward the flash of 

 light. A single flash stands for a dot, and a prolonged one 

 means a dash. While the French and Italian systems have 

 given very gratifying results, although not specially adapted 

 for use in the field, Mr. Gustin's method, on the other hand, 

 is designed especially for use at a moment's notice. Some 

 objections have been made against it by the authorities at 

 Washington, but the inventor thinks these have but slight 

 foundation. Elmira Daily Advertiser, October 3, 1873. 



THE AUTOMATIC SYSTEM OF TELEGRAPHY. 



The automatic telegraph system has been now for nearly 

 two years in operation between New York and Washington, 

 and it has proved itself a remarkable success. It is unques- 

 tionably the most rapid, unerring, and, at the same time, 

 economical system of transmission which has as yet been de- 

 vised or introduced into practical use. By it has been attain- 

 ed the rate of 1500 words per minute, on a line 250 miles in 

 length. The President's Message, of 12,000 words, was 

 punched and transmitted from Washington to New York in 

 about twenty minutes. 



Mr. Little's system consists principally in the use of a con- 

 denser for clearing the wire of a static charge of electricity, 

 and for the absorption of extra currents induced in the 

 helices of the magnets inserted in the main line. These 

 extra currents are brought about by making or breaking 

 the battery contacts. This condenser could be applied with 



