Polytechnic Association Proceedings. 703 



which it is attached is thrown to the right or left of the leading sec- 

 tion. The boat are especially adapted to canals in which there 

 are short curves, and has been introduced upon the Susquehanna 

 canal. The sections can be built one hundred feet in length, and 

 with the same crew and one horse or mule, additional two hundred 

 tons of freight or coal can be easily carried. 



SHIPS WINDLASS 



Mr. Wetmore presented a model of a ship's windlass. When 

 the capstan was rotated it turned a screw engaging the windlass- 

 barrel. Pawls are so arranged as to engage the ratchet-wheel of 

 the windlass, and so relieve the screw of strain when the vessel to 

 which it is applied is riding at anchor. Greater power and economy 

 of space were the claims over the old form of windlass. 



IMPR VED TR F-SQ UARE. 



Mr. John Burgum exhibited his improved try-square. In exterior 

 it resembles an ordinary try-square, but the peculiarity consists in 

 a double blade, with a square bar extending lengthwise through 

 the center of the space. Upon this bar are hinged a number of 

 cross-pieces, with a mortice in each sufficient to permit a small ver- 

 tical movement upon the bar. This bar permits these cross-pieces 

 to drop below the lower edge of the blade. Placed upon an uneven 

 surface, the unevenness is indicated by the raising or depression of 

 the cross-pieces. 



A UTOMA TIC B OILER-FEEDER. 



Mr. L. J. Knowles, then explained his patent boiler-feeder by 

 means of diagrams upon the blackboard. It consists of two brass 

 pipes connected at one end by a return coupling; the other ends 

 are connected one with the steam-space and the other with a water 

 space of the boiler; by this means the water in the apparatus 

 remains at the same level as the water in the boiler. To the end 

 of the upper pipe is attached a lever which regulates the feed-cocks, 

 and the end of the lower pipe stands against the valve of an alarm 

 whistle. If the water falls below the level of the upper pipe, steam 

 will enter and cause it to expand, moving a lever and starting the 

 pump, which will then fill the boiler and pipe, causing the latter to 

 contract, reversing the lever and stopping the pump. In case of 

 failure of the pump working, the water will continue to exhaust 

 until it reaches the level of the lower pipe, which will expand 



