768 BULLETIN OF THE BUREAU OF FISHERIES. 



latter is connected with the engine by two sets of pulleys and belts which 

 greatly reduce the speed (diagram, p. 766). 



A small gasoline engine furnishes the power. The engine speed of 324 revo- 

 lutions per minute is reduced to about 36 revolutions per minute in the trans- 

 verse shafting; then, by gears, to 18 revolutions in the longitudinal shafting, 

 and to 9 revolutions per minute for the propeller blades within the boxes. 



Four horizontal driving shafts running lengthwise of the float are each 63!/2 

 feet long. The transverse shafts connecting these back to the engine have a 

 combined length of 43 feet. The four large floats are only skeletons in struc- 

 ture. Both they and the houseboat to which they are attached float upon 

 the water and are subjected to considerable motion from the waves and from 

 the swells of passing vessels. A too rigid construction, therefore, is not per- 

 missible. Indeed, a friend of the station who is familiar with mechanical 

 construction facetiously observed that any reputable engineer to whom we 

 might submit the plans of our apparatus would without hesitation assert that 

 it probably would not work. However, it runs continuously with hardly an 

 hour of interruption for three or four months at a time. 



Several devices have been adopted which together make sufficient allowance 

 for the inevitable rocking movement of the floats and for the warping of the 

 light timbers, viz, comparatively light shafting (i inch), which in long pieces is 

 flexible; adjustable hangers; large-tooth cast gears; and the sliding shaft and 

 universal joint which has been mentioned. No trouble with the running of 

 the apparatus has ever arisen from the motion of the water, though the latter 

 is sometimes strong enough to break out the screen windows. 



DETAILS OF STRUCTURE. 



Houseboat.— A brief description of the houseboat with its materials and 

 dimensions is as follows: Two pontoons 52 feet long, 4 feet wide, and 4 feet 

 deep, of 3-inch hard pine calked, completely decked with 2-inch hard pine 

 calked ; each pontoon with 3 bulkheads and 4 water-tight compartments acces- 

 sible by hatches, painted all over, copper paint below water line; pontoons 

 placed 8 feet apart securely fastened by crossbeams and heavy knees at each 

 end; houses 10 by 10 feet near each end of the boat, with floors of 2 -inch hard 

 pine, roofs, sides, doors, shelves, closets, of North Carolina pine, painted out- 

 side, natural- wood finish inside; roof of house 7 feet from floor and having a 

 slight crown, covered with canvas and painted. An annex to the house (fig. 2, 

 pi. xc) on one end, made of lighter material and of the same dimensions, has 

 been added to give additional space for the engines and tools. 



Floats. — The four side floats, so-called, are merely skeleton rafts, buoyed 

 with barrels, whose construction may be seen in the diagram and on plates 



