Specification of Samuel Hall : apparatus for generating steam, gases, &c.

  • Hall, Samuel
Date:
1854
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Samuel Hall : apparatus for generating steam, gases, &c. Source: Wellcome Collection.

    6/28 page 4
    Hall's Improvements in Apparatus for Generating Steam, $c. must be so regulated as not to allow the artificial atmosphere to be lowered. This is to be done by cutting off such supply at a proper point of the stroke of the piston by any of the usual methods practised by engineers, so that the gasses and steam may act by expanding during the remainder of its stroke, and any superabundant steam may be allowed to escape by a valve into the atmo- 5 sphere. In order to illustrate the mode of first producing and then maintaining an artificial atmosphere of any required density and elasticity within the gene¬ rator and reservoir and connecting pipes, I must suppose those parts of the apparatus to be filled with air of the density of the atmosphere, and that by forcing air into them by an air-pump, or by any other suitable means, the inter- 10 nal pressure is brought up to the required point, which, for example, we will suppose to be one hundred and fifty pounds on the square inch, and we will suppose that air of the atmosphere condensed into a tenth part of its volume is of a density equal to one hundred and fifty pounds upon the square inch. Now, supposing the atmospheric cylinder to be ten times the internal capacity of the 15 working cylinder, and that the two pistons are put in motion by some extrane¬ ous power, every stroke of the atmospheric piston will cause the air contained in the cylinder in which it works to pass into the generator and reservoir and con¬ necting pipes, where it is compressed into one-tenth part of its original volume. When, therefore, it has passed through those vessels and pipes, the same quantity 20 escapes by the working cylinder at each stroke that is introduced by the atmo¬ spheric cylinder at each stroke; therefore the intermediate artificial atmosphere within the generator and reservoir and pipes will always be kept up to its pressure of one hundred and fifty pounds upon the square inch ; or in case the working cylinder be of the same internal capacity as the atmospheric cylinder, 25 the supply of air to the working cylinder from the generator and reservoir must be cut off by a valve or otherwise when the piston has made one-tenth part of its stroke, so that the atmospheric air compressed into one-tenth part of its bulk, which is so introduced into the working cylinder at each stroke of the piston, is allowed to expand during the remaining nine-tenths of the stroke 30 thereof to its original volume. This calculation, which is merely for the pur¬ pose of illustration, is made upon the supposition that no loss takes place from the imperfections of pistons and other parts of machinery, nor from the heat pro¬ duced and lost by condensation ; but as both of these effects will, of necessity, take place, an allowance in practice must be made for them. It may be proper 35 to mention here, that if in the above mode of illustration the working cylinder were of greater internal capacity than one-tenth of that of the atmospheric cylinder, and the supply of air were not cut off, the equilibrium between the natural and artificial atmospheres would soon be restored, by the latter being
    No text description is available for this image
    No text description is available for this image
    No text description is available for this image