Viewing page 97 of 140

This transcription has been completed. Contact us with corrections.

95.

[[image:  diagram of a cylinder G K H P, with a vertical pipe I L inside open at the top Z, with a dotted line M N  (liquid level), and a hole O above N.]]

But if there is made a vessel of copper G K P H, whose upper plate may be very thick to sustain a great effort;  and that there is put in it a hollow cylinder I L, ye vessel being full of water to M N, and there is a hole O thrô wch to syringue ye air by means of a [[space]] [[strikethrough]] whch [[/strikethrough]] wch shall be [[space]]; having stopped ye hole Z when ye air shall be 4 times condensed, its effort shall be equal to 4 times 32 feet of water; and if ye vessel was of a foot diameter each foot of water in height would weigh 55 pounds that would be therefore 128 times 55 pounds or 7040 pounds;  there would therefore be need of 7040 pounds to condense ye air 4 times:  But if ye hole O was 1/4 of an inch, and ye base H P one foot, ye proportion would be as 1 to 2304, and ye force of 4 pounds would make ye air enter to 4 times that number;  that is to say to carry ye weight of 9216 pounds;  it would carry therefore as great a weight as that of 128 feet of water are by consequence when ye hole Z was opened ye spout would go to near 100 feet.

  But if ye vessel was larger ye air wch should be between M N and C K, would not be more difficultly condensed by ye hole O, as is proved in ye Treatise of Percussion, and would not hinder its producing ye same effort to spout to 128 foot heigh as a pipe of all that largeness full of water.

  I made also ye following experiment.  I took 2 unequall syringues, one of 2 1/4 inches diamter, and ye other 3 1/4;  in that of 42 1/4 inches 5 pound weight made ye sucker descend and having filled ye syringue, and pushing ye sucker with a force near equal to 12 pounds, I elevated ye water thrô a hole of 8 lines, to near 4 feet:  Now a foot height of ye pipe of ye syringue is near as much in value as 32 ounces or 2 pounds and 4 foot are in value about 8 pounds:  If therefore ye effort was of 13 pounds, taking away 5 pounds for ye rubbing of ye sucker there will remain 8 pounds for ye weight equivalent to ye water of a reservatory of a little more than 4 foot heigh, and of 2 1/2 inches diameter:  Ye other syringue gave ye same in proportion.

Transcription Notes:
mandc: Revised image description. To help fill in the blanks, in the Desaguliers translation: "...inject air into it by means of a syringe there applied, and a valve within...." Image: http://echo.mpiwg-berlin.mpg.de/ECHOdocuView?url=%2Fpermanent%2Flibrary%2FQERNH1MN%2Fpageimg&mode=imagepath&pn=254&ww=0.1281&wh=0.1806&wx=0.7891&wy=0.486