Gambar halaman
PDF
ePub

in general in moderation will expedite the flow of the fluids in the uterine vessels, &c., and, also, that a sudden severe action will tend to urge it forward so quickly, before the vessels can convey it onward,

!

[graphic]
[ocr errors]
[ocr errors]

net

Tracings from Abdomen over the Uterus Pregnant at 9th month, showing the ordinary Respiratory Wave,

interrupted by movements of arm, leg, and of coughing.

[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]

that their rupture would result and effusion of blood be a natural consequence :-a result which experience shows actually occurs under such circumstances.

IV. “A Summary of an Inquiry into the Function of Respiration

at Various Altitudes on the Island and Peak of Teneriffe." By WILLIAM MARCET, M.D., F.R.S. Received March 31, 1879.

On the 19th March of last year, I presented to the Royal Society a short summary of an inquiry on the function of respiration at various altitudes in the Alps. The principal result obtained was that a greater quantity of carbonic acid was formed in the body and exhaled at the higher than at the lower stations. Thus, after experimenting on a spot near the Lake of Geneva, at an altitude of 1,230 feet, and at the summit of the Breithorn, at an altitude of 13,688 feet, there was found to be an excess of 15 per cent. for the carbonic acid expired at the highest station. I had come to the conclusion that the increased formation of carbonic acid in the body at certain altitudes in the Alps appeared necessary, as a means of resisting the influence of cold which is occasionally very great in high Alpine regions.

The question which now offered itself for inquiry was whether, on rising to a considerable altitude above the sea in a warm climate, there would be, as I had found in the Alps, an increase of the carbonic acid expired. After some consideration, the Peak of Teneriffe, in north latitude 28°, was selected as the place best calculated for investi. gating the subject. The advantages of this site were manifold. First, a mean temperature in the day time, which proved to be not lover than 64° in the shade, could be secured at an altitude above 10,000 feet; next as the mountain rose from the

sea,

various stations, beginning at the seaside, might be selected; then fine weather could be relied upon in June and July, on the Island of Teneriffe ; finally, the spot was situated at an accessible distance from England.

It took me three weeks to collect the necessary instruments, among which was a wooden shed, taking to pieces and made to pack in a comparatively small space. It consisted of six deal boards constructed so as to fit side by side with overlaping edges; when mounted, they formed a flat square roof. The four corners of this roof were supported by four poles held upright by tent ropes and pegs; broad strips of canvas were nailed to two opposite sides of the roof and spread out, being held in position by strings and pegs. The boards covered a square of 6 feet on each side and the sheltered area was much increased by the canvas. The shed was placed lengthways as nearly as possible in the direction of the course of the sun, and by this means we could work all day long in the shade, a necessary condition for the success of the inquiry.

My experimental baggage included two large baskets holding about 150 bottles of a capacity of rather more than 100 cub. centims. each,

and full of a titered solution of barium hydrate, in addition to which there were a number of empty bottles of the same size. The bottles holding the alkaline solution were carefully corked and the corks sealed with paraffin. I must also allude to two strong deal boards or rocking-boards, 6 feet in length and supplied with two iron sockets midway between the two ends; the sockets fitted upon an iron bar raised a few inches high on a firm wooden stand. Two square open wooden boxes were made to fasten at one end of each board respectively, and could be filled with stones or sand up to a given weight. The ase of these boards will be explained in the course of the present communication.

In addition to the above apparatus I carried with me a balance and everything required for determining the moisture expired from the lungs. My experimental baggage used in the Alps was also included, together with every requisite for camping out on the Peak for about three weeks.

My Chamounix guide, Edouard Cupelin, who has accompanied me for the last ten years in the Alps, and is thoroughly used to the mani. pulations connected with my experiments, came out with me to Teneriffe. He not only assisted me most effectually, but also submitted himself to experiment.

We arrived at the Island of Teneriffe on the 25th of June last, and after landing at Santa Cruz, proceeded at once to Puerto de Orotava, at the foot of the Peak. Three principal stations were selected, two at different altitudes on the Peak, and one at the seaside; while from the highest station instruments could be carried to the foot of the terminal cone, and also to the summit of the Peak 12,200 feet above the sea, where I proposed making a few experiments.

We remained eleven days at the lowest station on the Peak, at an altitude of 7,090 feet, and ten days at the higher station 10,700 feet above the sea.

The characters of the stations bearing on my experiments were :1. The topographical position and atmospheric pressare. 2. The temperature of the air. 3. The hygrometric state of the atmosphere.

1st. The position and atmospheric pressure. My lowest station on the Peak, that of Guajara, was situated on a sandy plateau at the foot of Mount Guajara, known from Professor Piazzi Smyth having established an astronomical station at the summit in 1856. The mountain rose 1,800 feet above my station in the S.W., while in the opposite direction for 200 or 300 yards, there spread a patch of white sand mixed with clay, and baked by the sun. Beyond that could be seen a bank of blocks of lava tumbled over each other, which formed the edge of an upper undulating level reaching the foot of the actual Peak at a distance of two or three miles. The heat of the sun at

on

that station was intense, as my tent was erected in a hollow, and the sand became so hot in the afternoon that the hand could not bear being kept in contact with it.

The mean of twenty-two readings of a Fortin barometer, by Casella, compared with the observations of Professor Smyth, taken at sea near the coast of Teneriffe, in 1856, at a similar time of the year, or nearly so, gave an altitude of 7,090 feet above the sea for that station. The stations in the Alps where my former experiments had been carried out, and corresponding in altitude with my Guajara station Teneriffe, were the Riffel (8,425 feet) and St. Bernard (8,115 feet), these however being rather over 1,000 feet higher.

The highest of my principal stations on Teneriffe was that of Alta Vista, where Mr. Piazzi Smyth also resided in 1856. This was near the summit of the Peak on a small “plateau,” occurring in a break between lava streams. This station faced an easterly aspect; in the evening a cold westerly wind often blew, sweeping down from the summit and feeling exceedingly chilly. The altitude of this station according to Piazzi Smyth, is 10,702 feet.

An accident to my barometer just before leaving Guajara put an end to barometrical readings, but an observation as to the temperature of boiling water at Alta Vista gave me exactly the height as determined by Professor Smyth. This altitude compares well with that of St. Theodule, 10,899 feet, one of my stations in the Alps.

The N.E. trade winds cause a belt of clouds to hover over the island ; I entered this layer of fog at an altitude of 3,200 feet, and left it at 5,500 feet, its thickness amounting therefore to 2,300 feet. My stations on the Peak were of course above the clouds; on one occasion only did I see them from Alta Vista make an irruption into the wide plateau at the foot of the peak between 6,000 and 7,000 feet high, but they soon withdrew.

2nd, Temperature.—The sky was cloudless till the last day, when a few light clouds appeared overhead, and the sun being nearly vertical at noon, in July, its direct heat was very great, although the air was much less warm in the shade ; on the other hand the cold W::3 very sharp at night. While the sandy surface of the soil was so hou at two or three o'clock in the afternoon, that the hand could not bear to be pressed against it, water left outside the tent in a bucket or in plates was on several occasions found frozen next morning just before sunrise. I had no black bulb thermometer in vacuo for observing the solar radiation, but Professor Smyth found on the summit of Mount Guajara over 180° F., with such an instrument by half-past nine o'clock in the morning, and he concludes that on August 4th, the black bulb temperature in the sun must have been 212°:4, the thermometer reading in the shade being only 60°, thus leaving the enormous quantity of 152° for the effect of sunshine at

sun.

a height of 8,900 feet. (P. Smyth—“Teneriffe-an Astronomer's Experiments.”)

Although my first station was 1,810 feet below that at which Piazzi Smyth's observations were made, I cannot think the direct solar heat was notably less.

I procured at Puerto a large box, and had it perforated with many holes on every side to allow of free access of air into it. This box was used as a screen for my thermometers; if I mistake not, a similar plan had been adopted by Professor Smyth. The screen was placed under my wooden shed, and thereby sheltered from the

While on my Alpine stations, I was working under a mean temperature of 39 at St. Theodule, and 52° and 43° at the Riffel and St. Bernard respectively, my atmospheric temperature on the Peak of Teneriffe was from 65° to 69° in the shade, and rose in the sun much higher than on the Alps ; in fact I was throughout the day time exposed to a climate much warmer than at my Alpine stations ; so far, therefore, my object, in going to Teneriffe, of avoiding cold at comparatively great altitudes above the sea was attained.

3rd, Moisture. The great dryness of the air in the daytime was very remarkable, the total mean difference between the dry and wet bulb readings at Guajara (7,090 feet) being 25°.6, and at Alta Vista (10,700 feet) 1997; while at Puerto de Orotava, at the seaside, the difference fell to 8°:7. I was never conscious of perspiring, and my skin was always very dry, with the throat parched at times. The evaporation from the skin must have been very great so high above the sea, in such dry air and under so powerful a sun.

The inquiry may be divided into three parts: The first refers to the respiratory phenomena at the various stations while in the sitting posture. The second, to the respiratory phenomena observed while engaged upon a definite amount of muscular work. The third, to the amount of watery vapour expired sitting at my different stations. I shall beg to commence with the experiments relating to the breathing while in the sitting posture.

The method adopted in these experiments was precisely the same as that I had made use of in the Alps, with this very slight difference, that instead of cooling the air expired into the bag, to the temperature of the water in the aspirator, where it was treated with the solution of barium, I noted the temperature of the air in the bag immediately after filling it, and drew the air at once from the bag into the aspirator or tube, recording its temperature in the tube. In nearly every case the temperature in the tube was rather lower than in the bag, so that a contraction took place ; the degree of contraction was duly taken into account in the calculations of the analysis. I also used common water instead of a solution of salt for aspiring the air for analysis into the tube.

« SebelumnyaLanjutkan »