522 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of power, and which may be applied to the driving-wheels 

 of the engine, and be under the control of the engineer. A 

 shaft runs under the whole car, connecting with wheels at 

 both ends by endless chains and slotted wheels, and also 

 havins: screws w^hich force the brakes aorainst the wheels. A 

 quarter turn sets the brake tight against the car-wheel, and 

 a similar backward motion releases it. By a simple device 

 all the cars in a train, as well as the engine, can be connect- 

 ed with it. The material is of wrought iron, and the invent- 

 or manifests his confidence in the apparatus by depositing 

 $50,000 in the Woburn Bank, subject to the order of any rail- 

 road company that will try it, and not find it jirove to be the 

 most nearly perfect brake ever devised. 



PEOTECTION OF SHIPS AGAINST TORPEDOES. 



The introduction of torpedoes into modern warfare has 

 evoked much efiTort in the way of methods for counteracting 

 their agency. It is suggested that the bottoms of vessels 

 most exposed to torpedoes be constructed with double cells, 

 the lower one being filled with water; this would act as a 

 bufier, and would distribute the blow of concussion, and ren- 

 der it less injurious to the fabric of the vessel. 16 A^July^ 

 1872,392. 



EXPLOSIVENESS OF WET GUN-COTTON. 



The discovery by Professor Abel, of the Woolwich Ob- 

 servatory, made several years ago, that compressed gun-cot- 

 ton fired by means of a detonating fuse exercised an extraor- 

 dinary shattering power upon objects with which it was 

 in contact, has been applied to a great many practical pur- 

 poses, in consequence of the facility of manipulation. One 

 special advantage claimed w^as the fact that the same cotton, 

 Avhen ignited by an ordinary match, would burn scarcely 

 more rapidly than ordinary cotton, and with no explosive 

 action. Several instances of disaster, however, have lately 

 occurred in preparing and using this material, Avhich tend to 

 show that it is not quite so safe to handle as was originally 

 anticipated. 



Recent discoveries at Woolwich have somewhat restored 

 confidence in this substance. Mr. E. O. Brown, of the arse- 

 nal, has found that compressed gun-cotton containing fifteen 



