296 Perkins's Improvements in the 



two tubes, k and /: it will be seen that the end of the tube k is tapered 

 off both inside and out to a sharp edge, which buts against the straight 

 surface of the end of the tube /. On the ends of these tubes are cut 

 screws, the one having a right-hand screw, the other a left-hand screw, 

 and by means of the coupling piece m, which has a female screw cut right 

 and left, the two ends of the tubes k and ( are brought together, and by 

 this means a strong water-tight joint is made ; and in this manner I connect 

 any number of tubes together, according to the purpose to which the 

 apparatus is to be applied. 



" d and e (Jig. 45.) are two views of the connections of other parts of 

 the apparatus, and also of the part of the apparatus which is intended for 

 the expansion of the water ; n is an upright tube, closed at the top, having 

 a small screw hole to let out the air when the apparatus is filled with water, 

 but which is kept perfectly closed when the air is driven out. This tube 

 n is usually made of a larger size than those in which the circulation takes 

 place, and in this tube there should be an area equal to the quantity of 

 expansion which will take place in the water contained in the outer tubes ; 

 and, as water expands to about one twentieth without being converted 

 into steam, I leave at least double that quantity of capacity in the tube or 

 vessel n. o o are short tubes formed into cones at their two ends : these 

 cones enter into holes perforated in the tube n, and into the ends of the 

 tubes p and q ; the tube p being the one by which the hot water is conveyed 

 from the coil a, after it has become heated, and the tube or pipe q is the 

 point at which the apparatus is filled with water, and by which the height 

 of the water is regulated ; and this tube q is to be placed in such a posi- 

 tion, that there shall be sufficient space above it, in the tube n, to allow for 

 expansion. 



" On the tubes p and q are two collars (r) formed, and by means of the 

 two plates s s, and the screw bolts and nuts t t, there will be a strong 

 water-tight joint formed to all the parts. At the top (v) of the pipe, there 

 is a collar (r) formed, and by the plates w, and screws and nuts x, the cone 

 y is strongly held in the opening of the tube q, by which the same is made 

 water-tight when the apparatus has been filled with water. To the bottom 

 of the expansion tube n is connected the pipe b, by coupling similar to that 

 described in c (Jig. 45.). >. 



" Having now described the manner in which I conceive it best to con- 

 struct the various parts of the apparatus, I shall now proceed to describe 

 some applications of the same, f (fig. 46.) shows a longitudinal view, and 

 g shows a plan of an arrangement for applying my improvements to hot 

 plates which are intended to be used by copper-plate and other printers, 

 for the purpose of heating the plates from which impressions are to be 

 taken. I have not thought it necessary to show the presses, or any other 

 parts of the machinery used for printing. The plates (a a) being intended 

 to be used in place of the charcoal fire-grates heretofore employed for 

 heating the plates at the time the ink is rubbed in, one of these heated 

 plates (a) is placed in the proper position at each press, if more than 

 one is to be heated ; and it will be evident that a large number of presses 

 may have their plates (a) heated by one set of tubes. The tube p is the 

 one which, as above described, conveys the heated water from the furnace, 

 and the tube c returns it back to the coil after it has given off its heat. 



" The manner in which I construct the plates (a) is as follows. I make 

 a rectangular mould to the size required, and place therein the bent part of 

 the tube p, and then fill the mould with melted lead, or other metal, accord- 

 ing to the degrees of heat such plates are intended to bear, by which 

 means I produce metal surfaces, which become heated by the passage of 

 the heated water through the tube p ; and it is evident that such heated 

 plates may be applied in a variety of ways, and for a variety of pur- 



