From the Hydro-spirometer, by T. Lewis MD., British Medical Journal, Volume 2, 1861, page 255.

“The new form of spirometer I am about to bring under your notice, is constructed on the principal of displacing a certain quantity of water by an extreme effort of expiration from a graduated glass jar. The jar is graduated in cubic inches, the enumeration proceeding from above downwards, and the results of the experiment is read off the graduated scale.

“Description of the instrument. The jar is about sixteen inches in height and five and a half inches in diameter. It is closed at the top by a metallic cap, which is perforated by three holes, into which are inserted corresponding tubes, as will be seen in the diagram.

“While in operation, the instrument is laid almost horizontally on the table, having been previously filled with water up to the level of the mark which indicates the commencement of the scale. The glass mouthpiece at the extremity of the elastic tubing is then placed in the mouth, and, after an extreme inspiration, the fullest expiration is made. There is no necessity for any precautions at the close of the expiratory effort. After the effort, the instrument is replaced in the erect position, in order to read off the amount of air introduced into the jar. There is no necessity for any correction on account of temperature, as it assumed that the air proceeding from the lungs is nearly always the same temperature.”