L. MECHANICS AND ENGINEERING. 463 



out on all sides. In order to catch the vibrations passing to 

 one side of the muzzle and cause them to be propelled for- 

 ward, it was proposed to enlarge the mouth of the gun into 

 the form of a widespreading cup. It is not easy to ascertain 

 precisely the distance in front of the muzzle at which the ex- 

 panding gas strikes with the greatest force; but it is tolera- 

 bly clear that when this point is once ascertained, it may be 

 made the focus of a parabolic cup. A series of small exper- 

 imental cannon with plain muzzles, conical and parabolic 

 mouths, were then cast, and it was found that conical cups 

 had a decided superiority over parabolic cup-shaped mouths. 

 Experiments were also made on the comparative merits of 

 gunpowder and gun-cotton, the experiments with the latter 

 substance being carried out by Professor Abel ; the result of 

 which latter was that the gun-cotton, when exploded in the 

 focus of the parabolic reflector, was decidedly superior to the 

 efiect of gun-cotton exploded in the open air, and in either 

 case superior to that of gunpovv^der. A further series of ex- 

 periments at long ranges, however, showed that while conic- 

 al mouths, as above stated, are superior for short distances, 

 the parabola gained the victory at long ranges. Experi- 

 ments made on the kind of wad showed that a wooden block 

 was superior to a junk wad ; the latter, in its turn, being su- 

 perior to the 2)a2ne7'-mache wad. In conclusion, he stated 

 that the experiments thus far made must be considered as 

 only preliminary to those necessary in order to arrive at a 

 full knowledge and definite conclusions on this important 

 subject. Journal Royal United Sermce Tnst.^ 1875, 481. 



CARRIEE-PIGEOXS. 



M. Laussedat communicates to the French Society for 

 Aerial Navi^ration the result of some observations on the 

 flights of carrier-pigeons. lie states that he has been en- 

 gaged in organizing a system of carriers for military pur- 

 poses. Twelve pigeons Avere taken from Paris to Moulin, 

 distance two hundred and seventy-one kilometers. The di- 

 rect line from Moulin back to Paris beinsj marked out for 

 the use of the trained pigeons, they were observed to follow 

 the mark very closely, and, according to a dispatcli sub- 

 sequently sent back to Laussedat, who remained at Mou- 

 lin, it appears that seven of the pigeons arrived together 



