Part 7

3. The quantity of water in the air was 1/20th less than the average, at the same time that the mean weight of a cubic foot of air was 2 grains above the average.

4. An unusual alternation of heat and cold, yet the heat predominating to such an extent that in particular localities it rose as much as from 2° to 8° above the average. These excesses were most striking at night, particularly in the parts of London on a level with the Thames, where the night temperatures ranged from 7°, 8°, 9°, and 10° above the temperature of the country, and even of the suburban districts. These temperatures were highest, especially the night ones, when the mortality was greatest; and the mortality was greatest where the temperatures were highest.

5. A remarkable increase above the average in the temperature of the water of the Thames. From a long series of observations it had been found that the normal temperature of the Thames is 51.7°. During the prevalence of the epidemic it rose to 60°, 66°, and once to 70°. At this temperature the “simmering” water must have poured enormous quantities of vapour into the surrounding atmosphere; not the pure vapour of water, for that cannot arise from a river which is the recipient of the foul contents of all the sewers and cesspools of the metropolis. In some instances there was an excess of 20° of the temperature of the water above that of the air. For twenty-eight continuous nights during the height of the epidemic, the average excess exceeded 16.5°.

6. An unusual prevalence of haze, mist, and fog; the fog being sometimes so dense that London could not be discerned from Greenwich.

7. An extraordinary stillness and stagnation of the air, both by day and night. Sometimes in the low-lying districts not a breath could be observed. Even when at more elevated stations the wind was moving with a force of 1 lb 7 oz., the pressure was only ¼ lb in the heart of London.

Wind is the ventilator of nature. Artificial ventilation, as far as it is successful, is an imitation of nature’s process. It is stated on undoubted authority (Maitland’s History of London) that for several weeks before the Great Plague broke out in London, there was an uninterrupted calm, so that there was not sufficient motion of the air to stir a vane. Baynard, a contemporary physician, confirms this fact. The like circumstance is mentioned by Diemerbroeck in giving an account of the plague at Nimeguen. At the period when the last plague visited Vienna, according to Sir Gilbert Blane, there had been no wind for three months. The terrific outbreak of the cholera at Kurrachee was preceded for some days by such a stagnation of the atmosphere that an oppression scarcely to be endured affected the whole population. It is obvious that calms must favour the accumulation and concentration of effluvia from every source from which they arise.

8. A general deficiency in the tension of common positive electricity.

9. A deficiency of one fourth of the rain-fall for the year. During 118 consecutive days there was scarcely any rain, and not a single drop for 18 days at the period of the highest mortality.

10. A total absence of ozone at all the stations near the river, while at stations of high elevation it was of general occurrence.

These observations relate particularly to the epidemic of 1854, which was more carefully watched than the two former; but the results are similar for each.

“The three epidemics,” says Mr Glashier, in summing up the results of his inquiry, “were attended with a particular state of atmosphere, characterized by a prevalent mist, thin in high places, dense in low. During the height of the epidemic, in all cases, the reading of the barometer was remarkably high, the atmosphere thick; and in 1849 and 1854 the temperature above its average. A total absence of rain, and a stillness of air amounting almost to calm, accompanied the progress of the disease on each occasion. In places near the river, the night temperatures were high, with small diurnal range, with a dense torpid mist and air charged with the many impurities arising from the exhalations of the Thames, and adjoining marshes; a deficiency of electricity, and, as shown in 1854, a total absence of ozone, most probably destroyed by the decomposition of the organic matter with which the air in these situations is so strongly charged.

“In both 1849 and 1854, the first decline of the disease was marked by a decrease in the readings of the barometer, and in the temperature of the air and water; the air, which previously had for a long time continued calm, was succeeded by a strong S. W. wind, which soon dissipated the former stagnant and poisonous atmosphere.”

We knew before that such influences were in operation, but they had not been weighed and measured. We now know definitely something of an epidemic atmosphere, and the information obtained is most significant; for it shows that the several meteorological changes that take place during the prevalence of an epidemic concur to produce a heavy, warm, moist, and stagnant atmosphere, with disturbed electricity: conditions highly favourable to the decomposition of organic matter.

Under the influence of such an atmosphere, over the moist and warmed surface of every filthy place, over the entire mass of all accumulations of filth in streets, lanes, and courts, and within and about houses, and over the heated surface of all foul water, decomposition goes on with the utmost activity, and the products are poured into the stagnant air.

Against such products the human body has no defence. The lungs admit whatever is brought to them—poisonous and salubrious substances alike. They are guarded by none of those protective contrivances which we see in some other parts of the body. Whatever is capable of suspension in the respired air passes with it directly into the current of the circulation, and when once there, is carried with astonishing rapidity into the very substance of the vital organs.

From the quantity of air which the lungs receive, some conception may be formed of the amount of obnoxious matter which may be introduced into the system through these portals.

At each inspiration there enter the lungs of an ordinary-sized person about 20 cubic inches of air. There are 20 respirations in a minute: 400 cubic inches of air must therefore enter in one minute; 14 cubic feet in one hour, and 366 cubic feet, or 36 hogsheads, in one day. To meet this the heart sends into the lungs at each contraction two ounces of blood; there are 75 pulsations in a minute, during which 150 ounces are propelled into the lungs; a quantity which gives 562 pounds in one hour and 24 hogsheads in 24 hours.

The main purpose for bringing these enormous quantities of air and blood together, with such velocity, is to provide for the enormous waste which is caused by the rapid and unceasing mutation of organic matter. The activity of an organ is sustained at the expense of the matter of which it is composed. No thought passes through the mind, but an equivalent portion of the substance of the brain is consumed; no nervous current flows along the nervous conducters, but a corresponding portion of nervous tissue is used up; no muscular movement, no glandular secretion, takes place without a proportionate waste of muscle and of gland. What must be the amount of supply required to meet this waste, when able-bodied men employed in their ordinary labour lose from 2 lbs. to 5 lbs. and upwards of their weight twice a day. Some physiologists of eminence have estimated that in order to supply that waste, there passes in the course of every 24 hours as much fluid through the thoracic duct as equals the whole quantity of blood in the body.

Footnote 8:

See Experiments on the daily loss of weight sustained by workmen employed in gas-works.—Philosophy of Health, 11th Edit. p. 284, et seq.

Footnote 9:

The tube which conveys the debris of the body, together with the nutritious part of the food,—both measures of change or waste.

The results of the highly interesting experiments recently made by Professor Graham on the part taken by the active agent in all these processes—organic membrane, of which the organic cell is the type, demonstrates that all the phenomena known as Endosmose and Exosmose depend on a chemical action involving the destruction of organic membrane. In this process chemical action is set up dependent upon active chemical agents, neutral substances being inoperative. Out of this chemical action a new force is induced, the Osmotic force; a purely chemical being converted into an equivalent mechanical force, which is made subservient to the essential phenomena of organic and animal life: a vis motrix, a force which is to the extra-vascular movements of the body, what the contraction of the heart is to the vascular.

In a frame so constructed, any particles contaminating the circulating fluid most rapidly pervade and contaminate every part of the system.

It has been sometimes imagined that the quantity of matter suspended in the atmosphere and conveyed into the system in respired air, must be too minute to exert any serious influence upon the body.

One single puncture of the finger, so small as not to be visible without the aid of a lens, has introduced into the system a sufficient quantity of putrid matter to cause death with the most violent symptoms.

A few drops of the liquid matter obtained by a condensation of the air of a foul locality, introduced into the vein of a dog, is stated to have produced death with the usual phenomena of typhus fever.

It is certain that on the introduction into the body of an inappreciable portion of the matter of cow-pox, or of small-pox, those specific forms of fever are produced.