Page:Popular Science Monthly Volume 44.djvu/523

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August 31, 1872.

My Dear Youmans: I am in the midst of my preparations here, and shall have them ready so as to enable me to start in the Russia on the 28th of September.

I shall need your friendly aid in getting my apparatus through the custom house. . . .

With regard to the lecture rooms, in all of them I must be able to lower the lights promptly. Most of my experiments will be projected on a screen.

I purpose mixing experiment and philosophy in due proportions.

I deal with the illustrative phenomena of light: the laws of reflection and refraction, analysis and synthesis, the bearing and significance of theories. Spectrum analysis and its revelations regarding the constitution of the sun. The higher phenomena of optics, interference and polarization, reaction of crystals upon light. The building of crystals. The extension of radiation beyond the range of the eye. The identity of light and radiant heat. This is a rough sketch of the subjects which will probably occupy me. I shall not know for a certainty until my preparations are complete.

Do your audiences look down upon the lecturer?

I suppose I can borrow an air pump in New York if I need it.

I suppose if they do not possess ice in Boston I can have a clear block sent there from New York.

Acids, of course, are to be had everywhere.

Are they in the habit of using compressed hydrogen and oxygen in iron bottles in America, and, if so, could I borrow such bottles?

I am taking one screen with me, but I shall sometimes require two. Is such a thing to be borrowed?

Now, like a good fellow, answer these questions within twenty-four hours, and oblige

Yours, ever faithfully,
John Tyndall.

And again:

Folkestone, September 19, 1872.

My Dear Youmans:. . . I hope they have clear ice in Boston, also nitric and sulphuric acid; if not, 1 must stock myself from New York. I have written a line to Dr. Draper on this point, but I should be truly thankful to you if you would make this point out for me, and if the acid is not to be had at Boston send there a carboy of nitric and one of sulphuric acid.

I am quite shocked at the mass of apparatus I have collected round me. Still I thought it best to take light apparatus—batteries, electric lamps, and costly optical apparatus—with me, having just given the experiments with them here.

Yours ever,
John Tyndall.

Prof. Tyndall arrived in October, and began his work at once by giving the Lowell lectures in Boston. Then followed courses in Philadelphia, Baltimore, and Washington.

Of his Boston lectures he says:

Boston, October 24, 1872.

My Dear Youmans: The hall of the Lowell still continues crowded, but I shoot above their heads sometimes.

In fact, this is my difficulty. I do not know the scientific level of my audience.

Still the people are most kind and attentive, and the newspapers, I believe, are very civil.