PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 447 



described, until the felloes bear firmly against the tire. The bolts F and 1 

 are then again set up tight by turning the nuts / and i: The nuts /* will 

 return to their original positions and a little beyond that, because the 

 radial movements of the spokes E, by withdrawing their wedge-like ends a 

 little, will allow the part H to slide a little further upon the part G of the 

 hub. 



It will be observed that the form of the wedge B is such as guards the 

 euds of the two adjacent felloes from getting out of line. 



By the construction herein described, I am able to compensate for the 

 enlargement of the tire and the shrinkage of the wood, and to readily make 

 the proper substitution when a part is injured. 



This removal and substitution of parts may be done •« the field, while an 

 action is progressing, and it is of very great importance, as it may very 

 often be the means of maintaining a gun in a serviceable condition whjch 

 would otherwise be useless, and, in other cases, may render it practicable 

 to retreat with a gun, which, in the absence of this invention, would be 

 lost. 



On motion, the subject was continued. 



Ends Stevens, Secretary pro tern. 



American Institute Polytechnic Association, ] 



January 9, 1863. ) 



The Chairman, S. D. Tillman, Esq., presiding. 



The preliminary hour of the Association was occupied as follows: 



Mr. Hoard exhibited a model illustrating the movements of a hydrostatic 

 engine, which, on motion, was referred to a committee consisting of Messrs. 

 Seely, Fisher and Bartlett for examination. 



Mr. Wiard exhibited apparatus for heating water, which elicited dis- 

 cussion. 



Dr. John B. Rich stated that Mr. Joseph Dixon, of Jersey City, a member 

 of the standing committee of manufactures, science and arts of the American 

 Institute, had constructed a musical instrument, on which much labor and 

 expense had been bestowed, and suggested that it might not be inappropriate 

 for a committee to be appointed to examine the same. 



Whereupon, on motion of Mr. Bull, the Chairman appointed a committee 

 consisting of Messrs. Rich, Bull and Rowell, to report thereon. 



Inland Navigation. 



In October, the attention of the Polyteclinic Association was called to 

 the subject of canal lock gates by Major R. Taylor, who presented models, 

 and explained their operation apparently to the satisfaction of the Associa- 

 tion, when an evening was set apart for the discussion of the subject of 

 inland navigation, on which occasion Major R. Taylor read a paper ou 

 canals, of which the following is a synopsis: 



He said his attention had been called to the subject in consequence of 

 having been interested in an improvement for operating the gates of locks, 



