Volume 1

Elements of physics, or Natural philosophy : written for general use, in plain or non-technical language / by Neil Arnott.

  • Neil Arnott
Date:
1864-1865
Catalogue details

Licence: Public Domain Mark

Credit: Elements of physics, or Natural philosophy : written for general use, in plain or non-technical language / by Neil Arnott. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    406/440 page 372
    being maintained, no inconvenience is felt. The inhabitants of some of the valleys among the Andes are as far above the sea as they would be at the top of Mont Blanc, where the atmo- sphere presses only half as much as on the sea-shore, but they enjoy good health. 814. There is a fact very simple and very important which deserves mention here. Sudden death occurs frequently during surgical operations above the heart-level, when a vein is acciden- tally cut into, and a little air is heard to whistle in, and so to reach the heart. It was long supposed that the heart had the power of sucking air in when such an aperture was made. This is error, but the fact is, that a vein descending from the head of a sitting person is as the descending leg of a syphon, and if it be wounded the air enters immediately. Such a fatal accident can- not happen where the person operated on is in a lying posture. 815. Water in the head is said to kill by fatal pressure on the tender brain: but, in reality, it kills by keeping out the blood, and so mechanically arresting the circulation. Ac- cordingly, we see, that where the fontanelle still remains open, or where the sutures or joinings of the skull will yield, water may accumulate to a great degree without causing much disturbance. A tumour in the brain, which would be of no consequence if the brain were unconfined, soon becomes fatal by occupying room in the skull, and to the extent of its size excluding or checking the supply of blood. If the substance of the brain at all increase and diminish in bulk, as muscles, &c., under certain circumstances, do, in the body below, all such changes must produce a considerable effect on the cerebral circulation and functions. RESPIRATION OR BREATHING. The chest is a cavity which alternately expands and contracts llice a pair of bellows, thereby tailing in and again expelling a certain volume of atmospheric air. This air comes nearly into contact with every particle of the circulating blood as that passes at every revolution through the spongy lobes of the lungs 'occupying the chest. These lobes consist chiefly of delicate air-cells and minute capillaries, so thin that air can act through their substance. Great changes are produced in the blood by the manner of contact described, and the animal warmth is one of the effects. 81G. As the motion of a windmill depends altogether on the
    No text description is available for this image
    No text description is available for this image
    No text description is available for this image