K. MECHANICS AND ENGINEERING. 417 



while the second was but little damaged, and would have 

 sufficed to prevent the passage of an attacking party. Eighty 

 pounds of gun-cotton were next treated in the same manner, 

 and fired, as required, by a detonating fuse. In this case the 

 explosion was terrific, and an almost perfectly clear breach 

 was made through both rows of timber, making it practicable 

 for an attacking party to go through. In another experiment 

 four beams of timber about sixteen inches square were sunk 

 in the ground, pressed together, and encircled successively 

 by necklaces of disks of the compressed gun-cotton. These 

 were exploded one after the other, and the beams were en- 

 tirely cut in two. Other experiments of much interest were 

 tried in the same connection, and all tended to prove the im- 

 portant applications of which the gun-cotton is capable. 

 3 A, May 20,370. 



TOEPEDOES AS MEANS OF DEFENSE. 



Experiments with torpedoes as a means of defense of har- 

 bors and coasts continue to be made, and it is now rendered 

 extremely probable that in future they are destined to play 

 a most important part in this connection. Elaborate inves- 

 tigations have lately been prosecuted by the military author- 

 ities of Great Britain, and the operators have succeeded in 

 determining with great precision the distances at which the 

 explosion of one torpedo is likely to disturb others set in the 

 vicinity ; and they have been able to arrange torpedoes so as 

 to permit of their being exploded at the instant of time that 

 an approaching vessel reaches a given spot, as shown by 

 sighting it through two telescopes at a certain distance apart. 

 3 A.October 28,307. 



PALE YELLOW FOR SIGNALS. 



It is stated, as the result of recent experiments, that pale 

 yellow is to be preferred to all other colors for signal lights, 

 as being the tint most quickly and readily recognized at a 

 distance. 3 B, August 8, 739. 



INDUSTRIAL NOVELTIES IN THE LONDON EXHIBITION OF 1871. 



Some industrial novelties displayed in the London exhibi- 

 tion of 1871 attracted much interest. 



Among the articles in the wool department upon which 



S2 



