112 ANNUAL OF SCIENTIFIC DISCOVERY. 



is 314 inches ; considerably less difference against the American 

 shot than the computed force shows in its i'avor, without charging 

 to the English shot the friction of the atmosphere against its long 

 sides. The worst of it is that this, by far their most powerful 

 gun, has not yet been made reliable. Scientific American. 



STRENGTH OF MODERN CANNON. 



Prof. Daniel Treadwell, at a recent meeting of the American 

 Academy of Arts and Sciences, read a paper " On the compar- 

 ative strength of cannon of modern construction," from which the 

 following table is taken : 



1 



2 

 3 



4 

 5 

 6 

 7 

 8 

 9 

 10 



1. Weight of gun, pounds. 



2. Weight of shot, pounds. 



3. Weight of powder, pounds. 



4. Initial velocity of shot, feet. 



6. Height to" which the shot would ascend if fired upward in vacuo. 



6. Force in pounds raised 1 foot. 



7. Force compared with a 32-pound shot under a velocity or 1,600 feet a 

 second. 



8. Force in number of horses working 1 minute. 



9. Number of pounds of shot raised 1 foot by each pound of metal in the gun. 

 10. Force of 1 pound of powder in foot pounds. 



The increase of resistance occasioned by rifling is not taken 

 into the account, although it makes an important item against the 

 Armstrong guns. 



LYMAN'S ACCELERATING CANNON. 



In the " Scientific American " for August 3, 1867, is a descrip- 

 tion, by the inventor, of the above cannon, which seems to promise 

 considerable changes in the form and operation of rifled guns. 

 From this account it will be seen that its performances are much 

 superior to the ordinary rifle, while the destructive strain upon the 

 barrel is much less. 



If the gun is 18 feet long and the bore is 6 inches diameter, it 

 weighs 33,000 pounds. 



Shot 300 pounds. Powder 100 to 120 pounds. 



Initial or breech charge 5 pounds, very slow mammoth. 



First accelerator 25 pounds mammoth. 



Second accelerator 25 or 30 pounds No. 7. 



Third accelerator 25 or 30 pounds cannon or mortar. 



Fourth accelerator 25 or 30 pounds mortar or musket. 



