Evening star. [volume] (Washington, D.C.) 1854-1972, 1856-03-21
ICnMNuNICATRn


previous, in relation to stopping tons Of
mailable matter at velocity of 700 feet per
second. / am obliged to Mr. r for his reply /;
at the same time L must say that it is alto
gether unsatisfactory, and 30 much ut variance
with all laws Of science, that, with your per-
dred thousand readers, that the Atmospheric
Telegraph, as exhibited in Mr.. R. . book, and
endorsed by the Senate Committee, il not by
any means adapted for practical purposes on
the scale that he proposes.
Mr.. 4 says that the mile of contained air
In the tube next to Washington will be en-
ployed a. an elastic buffer, to resist and over
come the momentum Of the load, The does not
say how this mile of air 10 known to be there, }
whether more or Less, and that this compressed
air will b allowed to escape tt rough the safe.
ty valve at = pressure of 40 lbs. to the square
inch, which amount of resistance will nearly
overcome the momentum of the tons, and
after it has passed the valve it will be an
| nounced by the ringing of the bell. Now, sir,
tons, at a velocity Of 700 feet per second,
ettains momentum Of nearly eleven millions
Of pounds; in other words, his mail bag of 7
tons moving from Baltimore to Washington at
the rate Of 700 feet in a second, will require
eleven millions of pounds to arrest 1t at W ash
ington. In his book, he nor his Senate COM
mittee do not say anything about stopping it
and, in reply to my first question, he offers
only Is 900 lbs. to stop it. You will readily
perceive that his 40 lbs to the inch of pressure
| will not answer at all. Hence the necessity
of some other reply to satisfy % Iago" and
the public. There will, Iopine, be something
more than the ringing of the bell to announce
the arrival of the mail bags of tons weight
| at ashingtOn, and l would say TO the post
master g stand from under at its arrival.
Now, by taking his book and explanation,
endorsed by the Senate Committee az data
and fsct: SIS a guide, his tube, 2 feet in diam.
eter aud 40 miles long, with a capacity of
64O, 200 cubic feet, and his 2 pumps with a
capacity Of $4,000 cubic feet, will be found
entirely ipaGeq uate to exhaust the tube in q
revolutions, or Twice q revolutions. The irst
revolution will perhaps exhaust As, 900 cubic
feet, and the air remaining in the tube will
become sufficiently rarefed SIS to fill the tube,
and the second revolution of the shsft will ex-
haust a far less quantity of air at a pressure
Of IA lbs. to the square inch, and so on with
every subseI uent revolution the air will be-
come more rsreaed Gnd less Of it will be ex.
hausted Now I hope that Mr.. r. and his
committee will be enabled &c see why his
load will not &c able to reach w ashin 2ton af-
ter leaving BaltiLSore a. soon as the shaft has
made q revolutions.
Now, sir, must beg leave most respectfully
to differ with Mr.. r, and his book endorsed
by that committee. have with all the light
at present in view arrived at the conclusion
that the Atmospheric Telegraph will never be
OF any great practical utility. / shall feel
proud to see his tons of mail beat a 2:40
horse on the course from Baltimore to W ash
,ugton. feel no little interest in the success
of Or. Rs invention; at the same time that 1
feel 1t to be impracticable. L am, however,
open 10 conviction, and shall be much pleased
to have my objections removed By Mr.. Rich
ardson. Most respectfully,
First Ward, March 20. IAeo.