96 ANNUAL OF SCIENTIFIC DISCOVERY. 



/ 



ease with which it can be cleaned, and, above all. in its arrangement for 

 making absolutely impossible the escape of gas at the joint between the 

 barrel and the breech. This latter is accomplished by a " self- ad justing 

 thimble," which is forced and held upon its seat in the breech-piece by 

 the reaction of the explosion. 



HOW GUNS ARE SPIKED. 



A correspondent of the Morning Herald says : " Spikes are about four 

 inches long, and of the dimensions of a tobacco pipe ; the head flat ; a 

 barb at the point acts as a spring, which is naturally pressed to the shaft 

 upon being forced into the touch-hole. Upon reaching the chamber of 

 the gun, it resumes its position, and it is impossible to withdraw it. It 

 can only be got out by drilling no easy task, as they are made of the 

 hardest steel ; and being also somewhat loose in the touch-hole, there is 

 much difficulty in making a drill bite as effectually as it should do. Its 

 application is the work of a moment, a single tap on the flat head with the 

 palm of the hand sufficing. This can be easily done, even if it is ever so 

 dark." 



NEW GREEK FIRE. 



The war in the East has stimulated the zeal of those in Europe who 

 are interested in improving the art of destruction. Projects the most 

 remarkable and curious are proposed. Being persuaded that one of the 

 means of preserving peace to humanity consists in perfecting our methods 

 of destroying life, and not desiring, in this respect, that one nation should 

 be more favored than others, we mention here some of the projects which 

 rest on serious principles. 



The Greek fire has, at different times, engaged attention, without its 

 being exactly known in what it consists. In 1755, a goldsmith of Paris, 

 named Dupre, discovered an inflammable liquid which burned under 

 water. Louis XV. allowed him to make experiments in the canal at Ver- 

 sailles, and then in different seaports, to try the power of the liquid in 

 setting vessels on fire. It is said the results produced were terrific. How- 

 ever, the king believed it his duty to refuse the advantages which the 

 invention promised. He withheld Dupre from publishing his discovery, 

 and gave him a pension. D upre died, and carried off his secret. 



In the month of April last, the photographer, Niepce de St. Victor, 

 while studying benzine as an ingredient of a varnish, observed that this 

 carburet which is very inflammable in the open air, and at a low temper- 

 ature, by the simple contact of a small flame, while being insoluble in 

 water, and having a density of 85 has, eminently, the property of burn- 

 ing upon water. He then remarked, that 011 throwing on water some 

 benzine containing a fragment of potassium, or of phosphuret of calcium, 



