From: The British Medical Journal, Sept 28, 1872, page 356.

“This admirable instrument may, with advantage, be brought under the notice of the profession generally, but especially of those whose practice and researches lead them much to the examination of the conditions of respiration.  The use of Hutchinson’s well known spirometer has, by its bulk and weight, been chiefly confined to public institutions, and there only to patients who could easily be brought to the machine.  The new and very beautifully designed instrument here illustrated is highly portable and singularly efficient.  It is constructed on the principle of Casella’s sensitive air-meter, first constructed for Dr. Parkes for measuring flow at the Netley Hospital, and now largely used in all public establishments.  It consists of finely balanced circular air-sail, which drives a hand over a dial, the graduations being obtained, by actual experiment, by means of machinery made for the purpose.  The dial shows the force and amount of respiration and capacity of the chest.  Casella’s spirometer is destined to supersede those now in use, and greatly to facilitate the clinical use of spirometry.”