430 Dr, Clarke upon a new Blowpipe, [June^ 



ment would have been anticipated. It is not to be expected,' 

 however, that the fusing powers of the two blowpipes can be 

 compared together ; but from the safety of TojVs blowpipe, a 

 child may use it ; whereas the other would be indeed a danger- 

 ous toy. 



In the old apparatus, when the instru- 

 ment is charged, the space E C G H is 

 occupied by air, and the water rises to the 

 dotted hne C D. When it has been kept 

 in action until the water has its surface 

 at the dotted line A B, the action ceases, 

 and the space E A F C must always remain 

 filled with common air. 



In the improved hydro-pneumatic appa- 

 ratus, which I have called TojVs bloivpipe, 

 when the instrument has been 

 charged for use, P P is filled 

 with air, and the 

 entirely above it 



small 



iiPlIll'" 24 Inches. 



12 Inches. 

 10^ Indies. 



water remams 

 in the vessel 

 Q, whence it will descend through 

 the cyhnder O E so long as any 

 air shall remain in the reservoir 

 P P, and the water will entirely 

 fill this reservoir ; so that what- 

 ever air it may be desirable next 

 to introduce will again displace 

 the water, and drive it up to Q without admixture of common 

 air. 



All gases are introduced by means of a bladder and a condens- 

 ing syringe, which screws on to the stop-cock F. And it has 

 been found better to introduce atmospheric air with a syringe 

 than to fill the reservoir with air from the lungs ; also to supply 

 the machine with water, or to remove it by means of a common 

 siphon. 



The instrument is so simple that a more minute description of it 

 is unnecessary. Upon these principles it is manufactured and sold 

 by Mr. Newmariy maker of philosophical apparatus, in Lisle- 

 street, Leicester-square. The usual size of one of these blow- 

 pipes is two feet high, two feet long, and five inches wide. 

 They are made either of copper or tin, and enclosed in a wooden 

 case, which serves as a table, and a rest for the arras ; the wax 

 taper, being sunk into a cylinder at X, is elevated or depressed 

 bv means of a screw and a rack. But a stationary spirit-lamp, 

 iJT it should be preferred, may be fixed in the same place. 

 I remain. Sir, yours, &c. 



Edward Daniel Clarke. 



