THE GREAT ADVANTAGE OF RAILWAY TRANSIT. 
233 
i otiier vessel containing mercury. The stem 
is calculated, to sink exactly as much as the 
' surface of the fluid flowing into the cistern 
rises above its bottom. It (the stem) is cy- 
I lindrical or prismatic, according to the form 
of the cistern, and must contain as many cu- 
bic inches as the measure of the quantity of 
I fluid which the cistern is to hold. In length 
: it must be equal to the sum of the height of 
I the fluid above the bottom of the cistern, 
I added to the space through which the sui’face 
i of the mercury rises in which it (the stem) 
swims during the filling of the cistern. The 
stem is itself set upon a float, which will 
support it and the empty cistern just at the 
surface of the mercury it floats in. I'he 
principle is, in fact, the same as that describ- 
ed in the account of the self-registering 
barometer given in No. 403 of the Mechanics' 
Magazine for April, 1831. It is, however, 
scarcely possible to procure, by ordinary 
means, a glass tube 20 inches or 2 feet long 
of a regular form ; therefore, when one is 
used as a cistern, a further adjustment of the 
stem becomes necessary, as described in that 
account. For the present purpose, the cis- 
tern need be only a few inches deep ; and as 
it may be made of wood or iron, it can be had 
of a regular form. 
It is hardly necessary to say, that in making 
calculations for the barometer the columns 
would be assumed at 28 and 31 instead of 
29*3 and30’5 inches. 
One sort of counterpoise may be worth 
noticing. It consists of a cylindrical ves- 
sel closed at one end, and of such dimensions 
(adapting it to the foregoing example), that 
29'3 inches in length of the inside shall con- 
tain in measure an equal number of cubic 
inches as 30*5 inches of the enlarged part of 
the tube. This vessel is to be attached to 
the other end of the chain by which the 
the tube is suspended (by the closed end), 
the chain being merely passed over a bar- 
rel or pulley ; it is then filled with mercury, and 
immersed, open part downward, in a vessel 
of the same fluid, and sunk by means of 
weights until the closed end comes on a level 
with the surface ; the column in the tube stan- 
ding at 29’3, as it is represented in the figure. 
If now the column in the tube rise to 30’5, 
the equilibrium being destroyed, it will des- 
cend through a space of 29 '3 inches, at the 
same time raising the vessel at the other end 
of the chain, with a column of mercury in the 
inside of it, supported by the pressure of the 
atmosphere, to a height equal to the space 
through which it descended, when the equili- 
brium will be restored. 
If the engine were made of dimensions suited 
to water, instead of mercury, a column of 24 
feet might be depended on in all states of the 
atmosphere. The head, whatever its dimen- 
sions, would woi'k with half its weight 
through a space of 12 feet; and if the foot of 
the tube were placed in an intermittent w^ell, 
or in a tide, which would rise and fall a cou- 
ple of feet, the engine would give a double 
stroke each time such rise and fall occurred ; 
the counterpoise working as well as the weight 
in the tube. 
W. M. G. 
London, Feb, 10, 1836, 
[^Mechanics' Magazine. 
RAILWAY TRANSIT.— It would require 
12 stage coaches, carrying fifteen passengers 
each, and 1200 horses to take 180 passengers 
240 miles in twenty-four hours, at the 
rate of ten miles an hour. One locomotive 
steam-engine will take that number, and 
go tw'o trips in the same time, consequently, 
will do the work of 2400 horses ! Again, 
it would require thirty mail coaches (six 
passengers each), and 3000 horses, to 
take 180 passengers and mail, 240 miles in 
twenty -four hours, at the rate often miles an 
hour. One locomotive steam-engine will 
take that number, aad go two trips in the 
same time, consequently, will do the work of 
6000 horses ! — T. M. Hackney. — Ibid. 
EXTENSIBILITY OF GOLD, SILVER, 
AND PLATINA. — The hundred-thousandth 
part of a grain of gold may be seen by the 
naked eye ; and a cube of gold whose side is 
but the hundredth part of an inch, has 
2,433,000,000 of visible parts. A cylinder of 
silver covered with gold leaf may be drawn 
out 350 miles long, and yet the gold will cover 
it. Gold leaf can be reduced to the three 
hundred thousandth part of an inch ; and gild- 
ing to the millionth. Silver leaf can be reduc- 
ed to the hundred and seventy thousandth. 
The specific gravities are 193 to 105. Lace- 
gilding is the millionth of an inch thick ; gold 
leaf the two hundred thousandth. Platina 
wire may be the fifty thousandth of an inch ; 
500 inches of gold-wire has been drawn from 
a grain. Tinfoil is the one thousandth of an 
inch, that is, 200 gold leaves are only equal 
in thickness to one of tin-foil. One grain of 
gold will cover Tf inches each way, or 52 
square inches, or be 1,500 times thinner than 
writing-paper, that is, a sheet of writing-pa- 
per would be 1 ,500 leaves. — Ibid. 
A 200 -SCAVENGER power.— M. Ber- 
nel, an Engineer at Lyons, has invented a 
machine, which, worked by one horse, collects 
and throws into a cart, in a given time, as 
much mud as could be collected by 200 
scavengers. — Ibid. 
IMPORTANT TO BAKERS.— A mecha- 
nical kneading trough has lately been in- 
vented by a baker of the name of M. Fontaine, 
at Paris, for which he has obtained a patent 
from the French Government. The chief 
advantages derived from this new invention 
are, that from 30 to 800lbs. of dough can be 
kneaded in the small space of 15 minutes, 
with the labour of only one man, and that with- 
out the least fatigue. It also causes the 
dough to be much better kneaded, conse- 
quently the bread is much better made than 
by the process usually adopted. The inven- 
tion is the fruit of long experience. — Ibid. 
