298 Hare’s Blowpupe. 
Explanation of the Plate at the end of the Volume. 
Fig. 1. Original compound blowpipe,. consisting of two 
common brass blowpipes soldered at their points into two 
perforations in a frustum of silver or platina,* after receiv- 
ing the blowpipes. ‘These perforations converge till they 
form one, the open end of which is their common orifice. 
Fig. 2. An enlarged representation of the frustum. It 
may be of brass, the orifice being protected by platina, as 
the touch-holes of guns are sometimes. The whole of the 
instrument being comprised in fig. Ist, injustice has evi- 
dently been done by those who have spoken of it as cum- 
brous or requiring simplification.+ 
Fig. 3. The compound blowpipe under another form. 
A. isa brass ball with two arms, furnished with coupling 
screws, for attaching the mstrument to the tubes through 
which the gases are to be supplied. B. is the pipe which 
receives and emits them as mixed for ignition. It is serew- 
ed into a perforation in the ball at right angles to another 
perforation bored through the common axis of the ball and 
arms. ‘This pipe is made of stout brass wire, drilled so as 
to admit a piece of hollow platina wire about three-fourths 
of an inch long, to be inserted at one end. The platina 
wire is rendered firm without solder, by passing the brass 
wire with the platina in it through a wire plate by the wire- 
drawing process. ‘The bore of the platima wire may be 
reduced to any size less than at first, by successive draw- 
ings through holes gradually smaller. Hence, by having 
the bore in the first instance made larger than can be want- 
ed in any case, it is easy to produce pipes with orifices of 
every desired diameter. 
Fig. 4. Exhibits the form above mentioned on a smaller 
scale, attached to the supply tubes. The latter have cocks 
and conical screws, for fastening them into a table, and also 
coupling screws, for connecting the instrument with the 
pipes employed to convey the gases to it, from the air hold- 
ers in which they may be kept. 
* The appellation, compound blowpipe, was given to this instrument by 
Professor Silliman, as he uses two blowpipes meeting in a frustum. 
tIt has been said that Mr. Cloud simplified it ; this is of course a gross 
error. If he simplified any thing, it was that part ‘of the apparatus in which 
the gases are confined. 
