HENJ. PIKE'S, JH., DESCRIPTIVE CATALOGUE. 



each end of it ; and also two 

 similar pulleys exactly at the cor- 

 ners. These are wholly hid frcm 

 observation by the tube when the 

 machine is finished, but the internal 

 arrangement of these, on one side, 

 may be seen in the cut. A little 

 smaller than the vessel described 

 above is another, made so as to 

 pass very easily up and down in it. 

 To the centre of this second vessel 

 in the top is fixed a rod, which 

 may be graduated, to show the 

 quantity of gas within the gasome- 

 ter from time to time. This rod 



passes through the cross-bar at top. 

 Near where tb 



the rod is fixed, are 

 two staples, having each a string 

 to it, which passes over the two 

 pulleys of its own side, and sup- 

 ports a weight at the other end. 

 Thus it will be seen that the side 

 tubes contain two weights, which 

 should be such as exactly to coun- 

 terbalance the vessel to which they 

 are suspended. A stop-cock is 

 fastened in the top to let out the 

 gas, when wanted for use, into 

 jars, bladders, or other apparatus. 

 This cock will also admit the gas 

 into the receiver from the apparatus, where it is being libe- 

 rated. To use the gasometer, first let the inner vessel fall 

 to the bottom of the outer vessel, and fill the latter with 

 water. Then open the cock, and fasten it to the tube that 

 conveys the gas from the retort. The gas rises, and gradu- 

 ally fills and lifts up the cylinder; and when sufficiently 

 filled, the cock by which it entered must be closed. The 

 gas may afterwards be drawn off as wanted. 



Price, $10.00 to $20.00. 



Compound Blow-Pipe. (Fig. 534, next page.) The com- 

 pound blow-pipe consists of two separate reservoirs, or gas 

 holders, each having at the bottom a neck, for introducing 



