MECHANICS AND USEFUL ARTS. 119 



The experience of all nations goes to prove that the most effect- 

 ive way of cleveloping^ ordnance power is by riliod guns. To 

 return to smooth bores, throwmg huge spherical masses of iron 

 wiih low velocilies, is to disregard all modern progress in the 

 science of gunnery, and to go back to the arms in use two cen- 

 turies ago. Furthermore, the advisability of using guns of such 

 great size is very doubtful ; for the slowness with which they are 

 handled and tired makes them less effective than smaller guns 

 delivering a more rapid fire. Two liundred of the guns required 

 it is proposed shall be Rodman 12-inch rifles, notwithstanding all 

 of that class of guns heretofore procured lor the army or navy, 

 and subjected to test, have either burst disastrously before the 

 lowest reasonable test has been completed, or have given such 

 indications of failing, after a few rounds, as to be considered 

 unsafe. It is proposed also to purchase GIO 10-inch Rodman 

 rifles, although the committee cannot learn that any gim of this 

 class has ever been subjected to test in this country, except the 

 Parrott rifles of that calibre, which are acknowledged failures, 

 having been condemned I^y both branches of the service. 



Ko progress toward obtaining better guns is likely to be made 

 while the ordnance bureaus are organized as at present; and the 

 conimittee deem the best way to secure such impartially con- 

 ducted experiments as will determine with certainty what are the 

 best arms, and to insure greater economy and regard for the pnb- 

 lic interests in their purchase and adoption, is in the formation of 

 a mixed ordnance commission composed of officers of high char- 

 acter, detailed from both the army and navy, who shall have no 

 interest in patents on devices for arms. 



CONCRETE BUILDING. 



Tail's system has been used in the construction of a large nimi- 

 ber of houses in Paris, erected under the directions of the em- 

 peror, who takes great interest in the improvement of the dwell- 

 ings of the working-classes, and has also been applied in other 

 parts of Europe, and to some extent in the United States. 



The work can be performed by ordinary laborers, who, after 

 4 or 5 days' experience, acquire all the requisite expertness. 

 Even boys have been successfully employed in this kind of 

 building. The only skilled workman necessary is a common car- 

 penter, whose duty is to adjust the framework or apparatus to 

 receive the successive courses of material, and place joists, doors, 

 and window-frames properly. 



The apparatus is designed to construct 18 inches in height 

 daily over the entire extent in hand. What is done in the even- 

 ing of one day is hard next morning, and quite strong, the best 

 proof of which is, that the wall itself, as it rises in height, sup- 

 l^orts the necessary scaffolds. A double curb, entirely surround- 

 ing the upper part of the walls, serves to hold the plastic material 

 in place, until it acquires sufficient hardness to support itself. 



