aqueous vapor of the tidal air enters the body at the pressure and temperature of the atmosphere, leaving it at the temperature of the body and pressure p1. A certain amount of water will therefore be evaporated in the lungs. The evaporation of this water and the warming of the tidal air will, therefore, absorb a moderate amount of heat which will play an important role in maintaining the equilibrium of the body.

Let us next consider the body placed (naked) in a very cold atmosphere. There will at first be a very rapid loss of heat at the surface, with the thermotaxic mechanism quickly checks by shutting off the peripheral circulation. But it is important that the moderate absorption of heat, which, we have seen above, takes piace during ordinary breathing, should be reduced to a minimum. This can be done by compressing strongly the tidal air in the lungs by means of the chest muscles and holding it so compressed for quite a long period, after which it is suddenly expelled and the process repeated. By holding it compressed it will have time to give up all its heat of compression to the circulation, and besides the aqueous vapor in it will be reduced to a minimum, viz., the amount necessary to saturate its small mass at the temperature of the body and the high pressure p..

By such a means of breathing the heat usually absorbed by the lungs is reduced to a minimum and, if the difference of temperature of the body and atmosphere are not too great, there may be even a generation of heat in the lungs.

As a matter of fact, after a plunge into cold water, or between the sheets of a cold bed, precisely such a peculiar kind of respiration is observed as could have no other effect than that mentioned above. The breathing consists of a deep gasp which draws in the greatest amount of air possible and then, all means of exit being closed, it is firmly compressed and held so for a long interval, at the end of which the tidal air is explosively expelled and the process repeated. It is evident that from the exaggerated compression a high initial temperature is acquired and, from the prolonged contact with the pulmonary capallaries ample time is given the air to part with all its heat above the temperature of the blood, and to condense the greatest amount of moisture possible, by means of the high pressure. The tidal air is then, under these conditions, launched out of the body suddenly, no time being given for it to take up any heat either by evaporation or expansion.

Let us suppose now that the body be placed in a saturated atmos

phere or water of a higher temperature than the body. Here no heat can be lost by evaporation by the skin, on the contrary heat is passing continually into the skin. The gain of heat is everywhere positive except in the lungs, and there heat enough must be absorbed to maintain the equilibrium. How shall the lungs work so as to effect this increased absorption of heat? First a deep inspiration so as to get a large amount of tidal air, but the most important part is the expiration. A sudden compression develops an instantaneous increase of temperature and with it an evaporation of water sufficient to saturate the air at the temperature and presThese two factors-temperature and pressure-to be sure, work in opposite directions, but the temperature is much the more important of the two. A large amount of water is momentarily evaporated, and this must be suddenly expelled, otherwise the air will have time to cool down and give back heat, first by condensation, second by conduction.

The writer has observed, under the conditions given, precisely this kind of respiration. Where a maximum effect is necessary, the respirations, each of this peculiar kind, are much increased in frequency. The case of the shaggy-haired dog has already been noted. The action of the heart is coincidently much increased in order to distribute rapidly the cold so gained by the lungs.

Recurring to our expressions for a and b above, we see that there must be a certain critical temperature for every warmblooded animal beyond which it cannot maintain its existence in a saturated atmosphere.

That is to say, theoretically, at this point it will be able to keep its temperature normal, while for a slight excess there will be a steady accumulation of heat in the body, which will result in death. by heat. Such death we know clinically takes place under three chief forms which may be merged into each other. First, death may be due to simple elevation of temperature. We know that the vital-chemical processes of the body can only take place within a very narrow range of temperatures, just as in the laboratory certain reactions require a definite temperature. When this temperature is increased the vital-chemical reactions in all the tissues are disturbed. The normal action of the brain cells is changed -coma results. The muscles also change their composition and their function of transforming the potential energy of various compounds into kinetic energy becomes deranged. Such a form of death takes place if the lungs and heart have been able to hold .

out thus long in the unequal contest.

When one or the other succumbs to the excessive strain put upon it, we have death by respiratory or heart failure, which are familiar enough forms to practitioners who have seen many cases of sun stroke.

Let us suppose that we have a saturated atmosphere of 80°, and that the ratio =, perhaps an average value. Under these conditions we find that_a=.145 and b=.132 a> b. Consequently heat will be generated with every breath and the individual could not long survive. 80° therefore is above the critical temperature for a human being where the tidal air is about half a litre and the ratio 1 cannot much exceed i

*

If A is the quantity of heat that enters or leaves the surface of the body (according to sign), B is the heat generated by the heart, and C is the heat due to katabolism, all in the time of one respiration, we may write A + B + C + m s,, ((—T) = (b—a) L, whereas L is the latent heat of water at temperature T. All these quantities except C are capable of direct measurement, and knowing the others, C can be found. When the body is at rest it is probable that this value is very small. For high temperatures also, certain experiments of the writer indicate that A is quite small. We may give then as an approximate value of the critical temperature of the human being 65°, or 70° (about 155° Fahr.).

It would be eminently desirable if observations upon a warmblooded animal could be carried out from a strictly thermo-dynamical point of view. Such experiments, requiring the conveniences of a laboratory, the writer has not had the opportunity of carrying out.

TO CONVERT FAHRENHEIT TO CENTIGRADE DEGREES.-A French publication gives the following simple rule for converting Fahrenheit to Centigrade degrees, which, however, does not apply so well to the reverse calculation: Subtract 32 degrees and divide by 2; then add to this one-tenth of itself, and, if further accuracy is desired, one-hundredth more. For instance, if it is required to find the number of Centigrade degrees corresponding to 72 degrees Fahrenheit, substract 32 and divide by 2, giving 20; adding one-tenth more gives 22, and, for greater accuracy, another one-hundredth gives 22.2.

* A small term-the heat necessary to raise (b-a) grammes of vapour from T to t.-is here neglected.

THE AMERICAN CLIMATOLOGICAL ASSOCIATION.

Fourteenth Annual Session, held at Washington, May 4-6th., 1897.

ABSTRACT OF PROCEEDINGS.*

First Day-Tuesday, May 4th.

President's Address.-Dr. E. Fletcher Ingals, of Chicago, after reciting briefly the history of the association since its organization in 1884, called attention to the great increase in our knowledge of the climatological possibilities in the United States, and urged the members to extend their studies to the effect of climate on various other diseases in addition to those of the respiratory and circulatory organs. The remainder of the paper was devoted to the antiseptic treatment and the limitation of climatic treatment of pulmonary tuberculosis. He briefly cited several cases illustrative of the benefits to be derived from the various antiseptics and from an antiseptic atmosphere, and urged upon the profession the inutility of sending patients at all advanced in the disease away from home, excepting under the most favorable circumstances. The paper closed with the following conclusions:

"In addition to tonics, supporting and anodyne remedies, various antiseptics appear to possess great value in relieving pulmonary tu berculosis, but in order to get good effects it is imperative that the system be as nearly saturated with them as possible. They should be given at first in small doses, but the amount should be steadily increased until the maximum dose is obtained, care being always taken not to disturb the digestive organs. For example, with the ci! of cloves we may begin with five drops given in capsules from three to five times daily, after each meal and in the middle of the forenoon and middle of the afternoon, the medicine always to be followed by a glass of milk. The second day the dose should be six drops; the third, seven; and so on until a dose of twenty-five or thirty drops is given each time.

"Creosote can seldom be given in sufficient quantities to have any material effect, because of the disturbance of the digestive organs which it is liable to cause, and because of its coagulating effect upon all albuminoids. The same may be said of carbolic acid.

* By courtesy of the Publishers-from Medical Record's Report.

"The carbonate of cresote is much more bland, and may be given in doses of from five to sixty drops after each meal with the greatest benefit.

"Guaiacol may be given in much the same way as the oil of cloves, though in somewhat smaller doses, but it is usually less easily borne than the carbonate of creosote or oil of cloves, and often cannot be tolerated in sufficient quantities. The carbonate of guaiacol may be used in much the same way as guaiacol itself, but most patients seem unable to take it in sufficient doses. Oil of cloves and carbonate of creosote are the most satisfactory antiseptics for internal administration.

"Iodine may be used as recommended by Shurley with undoubted benefit, but it causes considerable pain and is open to the objection that it necessitates too constant attendance of the physician. It may also be used advantageously as an inhalant.

"Patients should not be sent from home unless their financial and social position is such as to render the journey and sojourn easy and agreeable.

"In the first stage of the disease, patients should as a rule go to a high altitude, where the atmosphere is as warm as practicable. In the second stage they should be sent to a medium altitude. In the third stage, if sent anywhere, it should be to a low altitude, and in most instances to a dry atmosphere.

"When sojourning in a favorable climate the patient should be out of doors as much as practicable during the pleasant portion of the day, but should avoid excessive heat, excessive cold, and unusual fatigue.

"Patients who have been improving under any course of medication should not discontinue it upon going to a different climate, but however valuable any remedy may appear it should not be continued if it become clear that it is deranging the digestion.

"Of anodynes to check cough, hyoscyamus, camphor, cannabis indica, stramonium, and conium are of most value, because they can generally be taken in sufficient quantities without disturbing the digestion, whereas opiates are usually deleterious in whatever form they may be employed.

"The majority of patients sent from home in the later stages of pulmonary tuberculosis are injured by the journey and their lives. correspondingly shortened, though in a small percentage a very great benefit is obtained."

Dr. R. G. Curtin, in discussing the president's address, said that