Persistency determines the MOPP level; the degree of threat; and performance decrement caused by the protective measures used.
That the decrement of temperature with altitude is most rapid in summer: this (as I shall hereafter show) is not the case in the Himalaya, chiefly because the warm south moist wind then prevails.
This diminution is not the same for greater heights, as I shall have occasion to show in a separate chapter of this Appendix, on the decrement of heat with elevation.
It has been shown by experiment that this decrement is proportional to the temperature, and hence by the aid of capillary observations we are able to form an idea that at a certain rise of temperature the cohesion may become = 0.
This decrement in vapour tension which occurs in the intermixture of vapours and gases, although small, indicates that there is then already, so to speak, a beginning of chemical change.
In the United States, and in the south of Europe, the heat of the plains (from 40 to 43 degrees latitude) is nearly the same as within the tropics; and according to my researches the decrement of caloric equally varies but little.
Yet no intellect is able to perceive in any given lifetime the actual decrement of this angle.
Evolution is the decrement of this difference between the purely formal and the actual.
The nightly temperature was consequently seven degrees colder than that of the coasts, which is a fresh proof of an extremely rapid decrement of heat, the table-land of Cocollar being less elevated than the site of the town of Caracas.
The decrement of the heat being nearly the same within the tropics, and during the summer under the temperate zone, the small difference of level of one hundred toises should produce only a change in the mean temperature of 1 or 1.
The decrementof heat is also different above the plains of Africa, and above the surface of the Atlantic; and the strata of air, brought by the trade winds, cool in proportion as they advance towards the west.
According to the law of the decrement of heat, three hundred and fifty toises in height produce in this latitude only three or four degrees difference in temperature.
The springs which descend from the neighbouring mountains of a greater height often indicate a too rapid decrement of heat.
Less finds evidences of very rapid decrement of temperature during thunder storms, as shown by the examination of records of 120 stations for ten years.
Less has been able to satisfactorily answer in the affirmative an important point in the theory, as to whether the vertical decrement of temperature is especially rapid.
Only in the exceptionally perfect vacuum referred to above did this logarithmic decrement sink to about one-twentieth of what it had commenced with.
Repulsion of the vane by the action of light commences when this decrement is one-fourth of what it was before the exhaustion of air began.
If the species be evolving, the advance in individuation implies a certain economy, of which a share may go to diminish the decrement to genesis.
This last term is defined as the logarithm of the ratio of one swing to the next succeeding swing, and a galvanometer of which the logarithmic decrement is large, is said to be highly damped.
The quality of a galvanometer in this respect is best estimated by taking the logarithmic decrement of the oscillations when the movable system is set swinging.
