344 Patent for certain Improvements 



the cylinder or cylinders : for example, when steam of forty 

 pounds the square inch is used, such a quantity of tlie same 

 as shall h'j equal in volume to one-fortieth of the capacity 

 of the cylinder or cylinders, and so in proportion when 

 steam of any other force is eaiploved ; and when the re- 

 quisite quantity has been admitted, the steam is to he shut 

 off till the proper moment for admitting a fresh quantity. 

 But if it is intended that advantage shall also be taken of 

 the elastic force of the steam acting on one side of the piston 

 or pistons, while condensation goes on on the other side, 

 then the steam must be admitted more freely, but still with 

 caution at the first, for the reason already mentioned. And 

 in this, as well as in every other application of my said im- 

 provements, grounded on my said discovery of the law of 

 expansibility of steam, due and effectual means nnist be 

 used to keep up the requisite temperature of all the parts of 

 the apparatus into which the steam is admitted, and in 

 which it is not intended to be condensed. And here it may 

 be proper to state, that, instead of the obvious and usual 

 means for accomplishing this, namely, inclosing them in 

 the boiler, or in a steam ease or cases eonununicating viitU 

 the boiler, the following method may sometimes be used 

 with advantage, viz. a separate fire under the steam case 

 or cases, which, in that event, will become a boiler or 

 boilers, and must be furnished with a safety-valve or valves 

 to regulate the temperature. Bv means of the last-men- 

 tioned arrangement, the steam from the smaller cyhnderor 

 steam measure (when either of these is employed) may be 

 admitted into the larger cylinder or cylinders kept at a higher 

 temperature than the smaller, by which its power to expand 

 itself may'he increased; and, on the contrary, by keeping 

 the larger at a lower temperature than the smaller, its ex- 

 pansibility will be lessened; which, on particular occasions, 

 and for particular purposes, may be desirable. In every 

 case care must be taken that the boiler, the case or cases 

 in which the cylinder or cyhnders is or are inclosed, the 

 steam pipes, and generally all the parts exposed to the ac- 

 tion of the expansive force of the steam, be of a strength 

 proportioned to the hitih pressure to which they are to be 

 exposed. With regard to the due degrees of strength of 

 the parts of all my said improvements, together with the 

 nature of the materials, and the proportions of the same, 

 except as herein tlcscribed, I forbear any farther descrip- 

 tion, on account of the numeroiis variations tp which the 

 .same must be subjected ; and beeaucc every engineer, of 

 sufficient skill to be employed in works of this nature, will, 

 3 without 



