The instruments for measuring the vital capacity of the chest have been designed to measure the total amount of air propelled from the chest by the deepest expiration following upon the deepest inspiration. Our most important knowledge of spirometry was derived from Dr. Hutchinson's exhaustive paper in the Medico-Chirurgical Transactions of 1846. The instrument designed by Hutchinson consisted of a mouth-piece and tube communicating with a gasometer of registered and graduated capacity, into which the patient breathed. Mr. Towne has of late years invented a convenient and accurate spirometer, which works on the principle of the anemometer. The advantage of this instrument is its portability. As is well known theanemometeris a contrivance used by the meteorologist for indicating the rate or velocity and direction of the wind. Dr. Waldenburg has described a spirometer identical in principle with Hutchinson's, but elaborate and capable of being employed for the purpose