Alexander G. McAdie


John Muir


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Address correspondence toOfficial In Charge Local Office, Weather BureauU.S..DEPARTMENT OF AGRICULTURELOCAL OFFICE OF THE WEATHER BUREAUMerchants Exchange. Rooms 1500-6SAN FRANCISCO, CAL.March 19, 1910.Mr. John Muir,Martinez, Cal.Dear Mr. Muir:-I have not forgotten your request regardingthe number of water drops in a cloud; but I find it hard to get down to definite statements. I'd much rather talk it. over with you, and yet that wouldn't do either, for we'd get off on other matters of equal and everlasting interest.First, as you look up into the sky, remember that the seemingly limitless ocean of air, at the bottom of which we waddle, is not much deeper than the distance from one great peak in the Sierra to another. When you stood on Whitney you were up nearly four-tenths of the way, that is, nearly half of the so-called homogeneous atmosphere is below one at a height of 5,500 meters (31/2 miles). At an elevation of six miles nearly, two-thirds of the atmosphere is below us. At this elevation you are above what we may call "the muddy" or dirty part of the atmosphere. It is clean mud, almost entirely water. Most people call it clouds; but it is none the less a sediment of water and fine dust. Below the level named, the air is in a turbulent condition as a rule, convectional currents rising, falling and in fact swirling in every direction. I sometimes04734


San Francisco

Date Original

1910 Mar 19


Original letter dimensions: 25 x 20 cm.

Resource Identifier


File Identifier

Reel 19, Image 0255

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Owning Institution

University of the Pacific Library Holt-Atherton Special Collections. Please contact this institution directly to obtain copies of the images or permission to publish or use them beyond educational purposes.

Page Number

Page 1


John Muir, correspondence, letters, author, writing, naturalist, California, correspondent, mail, message, post, exchange of letters, missive, notes, epistle