Fortin's Barometer

Fortin's Barometer. The upper part of the cistern is formed of a glass cylinder, through which the level of the mercury may be seen. The bottom is made like a bag, of flexible leather, against which a screw works. At the top of the interior of the cistern is a small piece of ivory, the point of which coincides with the zero of the scale. By means of the screw, which acts on the flexible cistern bottom, the level of the mercury can be raised or depressed so as to bring the ivory point exactly to the surface of the mercury in the cistern. In some barometers the cistern is fixed, and the ivory point is brought to the level of the mercury in the cistern by raising or depressing the scale.
Source: 1911 EB, Vol. 3, Page 419

Other images in this category...

All of these images are completely free and may be used for any purpose, in whole or in part, royalty-free, without the need to give credit to their authors, under the laws of the United States. They come from old books whose copyright has expired in the U.S. (like the 1911 Encyclopedia Britannica) and from U.S. Government web sites.

No copyright. No rights reserved. All images and text are believed to be public domain under the laws of the United States. No warranty nor guarantee is given as to the accuracy of any of this information or imagery, nor for it's suitability for any purpose. Use at your own risk. For more information about copyrights, see our Terms of Use.

(Script last modified Tuesday, the 30th of August, 2011 at 7:41pm)