297 of the instrument. It has been subjected to severe tests, and answers the purpose completely. Until the matter was brought under my notice by Dr. Dupre's letter, I had not the slightest notion that a thermometer resembling my own had been constructed; and I think that gentleman will concede to me that, whi!e undoubtedly before me in applying the principle of insulation, he has not brought his instrument into a form which renders it suitable for general use in clinical practice. In saying

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... s, I do not for an instant wish to detract from the merit of the conception, to which he has a prior claim. Will you allow me to say that I anticipate some new clinical results from the use of my instrument as a spiro tbermometer. When held about an inch from the patient's mouth, the mercury rises with each expiration and falls with each inspiration, until, like a tidal wave, gaining something at each advance, it reaches the mean temperature of the breath, after which it rises and falls with every respiration, the time occupied and the length of the oscillation indicating, the manner in which the lungs act. I believe it will be found that it is by this instrument possible to ascertain the temperature of the breath without taking that of the mouth, which may be determined by local conditions. I am, Sir, yours obediently, Euston-square, Aug. 23rd, 1877.