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Дата написания1970-01-01
Язык книгиen
Возрастное ограничение12+
Жанры
зарубежная образовательная литератураастрономияестествознание

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Страница 23 из 23

2

Man's Place in the Universe p. 267 (1903).

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3

This is on the opposite side of Mars from that shown in the frontispiece.

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4

In 1890 at Mount Wilson, California, Mr. W.H. Pickering's photographs of Mars on April 9th showed the southern polar cap of moderate dimensions, but with a large dim adjacent area. Twenty-four hours later a corresponding plate showed this same area brilliantly white; the result apparently of a great Martian snowfall. In 1882 the same observer witnessed the steady disappearance of 1,600,000 square miles of the southern snow-cap, an area nearly one-third of that hemisphere of the planet.

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5

What the evaporation is likely to be in Mars may be estimated by the fact, stated by Professor J.W. Gregory in his recent volume on 'Australia' in Stanford's Compendium, that in North-West Victoria evaporation is at the rate of ten feet per annum, while in Central Australia it is very much more. The greatly diminished atmospheric pressure in Mars will probably more than balance the loss of sun-heat in producing rapid evaporation.

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6

Areas on Mars so named.

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7

In a paper written since the book appeared the density of air at the surface of Mars is said to be 1/12 of the earth's.

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8

Professor J.H. Poynting, in his lecture to the British Association at Cambridge in 1904, says: "The surface of the earth receives, we know, an amount of heat from the inside almost infinitesimal compared with that which it receives from the sun, and on the sun, therefore, we depend for our temperature."

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9

For a short account of this remarkable instrument, see my Wonderful Century, new ed., pp. 143-145.

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10

Keith Johnston's 'Africa' in Stanford's Compendium.

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11

Chambers's Encyclopaedia, Art. 'Deserts.'

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12

LaTex markup $\root 4 \of {1 \over 100} = {1 \over 3.2}$

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13

The effects of this 'cumulative' power of a dense atmosphere are further discussed and illustrated in the last chapter of this book, where I show that the universal fact of steadily diminishing temperatures at high altitudes is due solely to the diminution of this cumulative power of our atmosphere, and that from this cause alone the temperature of Mars must be that which would be found on a lofty plateau about 18,000 feet higher than the average of the peaks of the Andes!

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14

Nature, vol. 70, p. 536.

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15

Nature, vol. 70, May 5, p.xi, supplement.

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16

The coefficient of contraction of basalt is 0.000006 for 1° F., which would lead to the results given here.

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17

Mr. W.H. Pickering observed clouds on Mars 15 miles high; these are the 'projections' seen on the terminator when the planet is partially illuminated. They were at first thought to be mountains; but during the opposition of 1894, more than 400 of them were seen at Flagstaff during nine months' observation. Usually they are of rare occurrence. They are seen to change in form and position from day to day, and Mr. Lowell is strongly of opinion that they are dust-storms, not what we term clouds. They were mostly about 13 miles high, indicating considerable aerial disturbance on the planet, and therefore capable of producing proportional surface denudation.

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18

A four inches barometer is equivalent to a height of 40,000 feet above sea-level with us.

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