110 
of the jet. Select at the stationers 
‘bottles of India-rubber, varying in 
weight from half to three-quarters of 
a pound, preferring those of a dark 
hue; astrip of which, when pulled out, 
so as to become very ‘thin, is almost 
transparent; and avoid those bottles of 
a browner colour, a strip of which can- 
not be pulled out so thin as is men- 
tioned above without breaking. ‘Che 
bottles selécted are to be boiled in wa- 
ter until quite softened, which usually 
occurs after a quarter of an hour's 
boiling. A ‘short btass tube, having a 
stop-cock on its middle, and a screw- 
tap adapted to screw into a condensing 
syringe at one end; and having, near 
to the other end, a milled projecting 
rib-outside, provided for each bottle; 
and, when these are cooled after the 
boiling, the ribbed end of a tube is in- 
serted into the neck of each India- 
rubber bottle, and is firmly secured 
there; by lapping strong waxed thread 
above and below the rib. 
The tube of one of the bottles is now 
screwed ‘to the syringe, and air is 
forced in; after a few strokes of the 
syringe, a blister-like projection will 
be observed to form on that part of the 
bottle which is the thinnest; and, as 
the forcing-in of air is slowly conti- 
nued, the blister will be seen to en- 
large, until it extends over the whoie 
surface, and the bottle will usually 
then have acquired a diameter of four- 
teen to seventeen inches: in this state, 
the blow-pipe bottle being completed, 
it is unscrewed from the condenser, 
and the jet-pipe is screwed on in its 
place ; and now the blow-pipe is ready 
for use; and immediately, on turning 
the stop-cock, the elastic contraction 
of the bottle will force out the air ina 
strong and steady jet, as has been 
mentioned above, which will continue 
until the bottle is reduced to about 
double its original size ; when the con- 
denser may be again applied, and the 
bottle be again distended as before, 
untess that several bottles have been 
prepared and charged at first, as is 
mentioned above. When no longer 
wanted, the bottles should be emptied 
of their air, and so may be kept for any 
length of time ready for charging; 
only observing, that if at any time a 
bottle has lost its pliability, and be- 
come hard by keeping, it must be im- 
mersed for a short time in boiling wa- 
ter before applying the syringe. The 
great portability, and the length and 
steadiness of action, of this blow-pipe, 
are its great recommendation: itmay be 
Blow Pipe.-—Life Annuities. 
[Sept. T, 
used with any of the gases, even ex- 
plosive mixtures of oxygen and hydro-~ 
gen, the accidental explosion ef whiich 
would merely burst and destroy the 
bottle, without occasioning further 
mischief. Z. A. 
—_ 
To the Editor’ of the Monthly Magazine. 
SIR, 
HE exertions against the repeal 
of the Usury Laws, in whieh you 
_ have borne a conspicuous part, have 
happily been crowned with success; 
and, however seldom we have to praise 
the conduct of our legislators, we must 
do them the justice to say, that they 
in a firm and determined manner 
resisted the wicked attempts of avari- 
cious speculators to extort from neces- 
sitous borrowers a higher interest than 
five per cent. Itis to be hoped they 
will be for ever deterred from renew- 
ing their attempts; or, if they again 
expose themsclves, that the legislature 
will again put them to shame. There 
are only two circumstances that can 
justify the expectation of a higher in- 
terest than five per cent. the first 
is, that the money is locked up, and 
cannot be recalled on giving notice, ag 
in the case of mortgage and similar 
loans; and the second is, when 
the interest is to be paid, not for a 
perpetuity, but for a limited period, or 
a period depending on the contin- 
gency of the existence of one or more 
lives. ‘There are, comparatively, few 
persons, who can afford to have their 
money locked up, so as not to be 
called back when they want it; and who 
are willing to risk its loss, by the ex- 
tinction, by death, of the persons on 
whose lives the annuities depend; 
hence the gain, from investing money 
in this way, naturallyrises much higher 
than it otherwise would; and it is a 
very advantageous speculation for 
those who adventure init. here are 
many so situated in regard to their 
property, that they can raise money 
only by way of annuity. 
There are ample and important rea- 
sons, in addition to the difficulty of 
procuring money at five per cent. for 
any given length of time, which induce 
many individuals possessed of un- 
doubted freehold and copyhold securi- 
ties, as well as public bodies, to prefer 
raising money by way of annuity. 
For example, if a gentleman raise 
money by. mortgage, he cannot gene- 
rally be secure against being called 
upon ‘to repay it for mote than six 
months, 
