MACHINE FOR HAND LABOUR. 



293 



the principle of the tread-mill, which, though heavy labour, is the 

 most effective manner in which the power of men can be applied. 

 I am indebted for the suggestion of this machine for raising marl 

 to the observation and scientific knowledge of mechanics of my 

 friend Professor M. Tuomey, and also for the following description, 

 and the drawings for the engraved figures. Mr. Tuomey, when 

 making a transient visit to the fortress, had seen the machine at 

 work; and after reading in the foregoing part of this work the 

 remarks on the different modes of raising marl, and having wit- 

 nessed some of the usual modes in practice, this machine and what 

 he had seen of its power appeared greatly superior, wherever cir- 

 cumstances may require the use of machinery. Upon being thus 

 informed, I applied to Dr. Robert Archer, U. S. A." Surgeon at 

 Fortress Monroe, for a rough plan, and accurate statement of the 

 dimensions of the machine, both of which he kindly furnished; 

 and with the aid of these, Mr. Tuomey has been enabled to give 

 such particular description and correct delineation as will serve for 

 full instruction for the building and working of the machine. 



Fig. 1. 



" 1. Figure 1 is a side view, in perspective. 



^ i, The base, consisting of 3 pieces of scantling, each 12 feet long, and 

 11 inches by 5, notched on to each other about 6 inches from the end, so 

 as to be flush on top, forming an equilateral triangle. 



e, The principal post 8 feet, 8 by 6 inches, secured to the base, and braced 

 by the braces /. Near the top of this post 2 iron sheeves or pulleys are 

 placed, one on each side, and secured by pieces spiked over them. The 

 chains pass over these pulleys. 



/. 2 braces 11 feet long, 4 inches by 6. 



h, h, Two uprights, in which the gudgeons of the wheel turn; they are 

 bolted to the base and connected at the top by the piece g, 10 feet 6 

 inches long, 4J by 6 inches, which also serves as sThand rail for the men 

 to steady by when working on the wheel. These uprights are further 

 secured by cross-pieces connected with the braces, and bearing in front 

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