Page:Popular Science Monthly Volume 23.djvu/351

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337
MACHINES DRIVEN BY SOLAR RAYS.

rationally. If lie had lived now, a corresponding education would certainly have put him in possession of the very simple facts which I have placed before you; and the application to them of his own methods of reasoning would have taken him as far as we have been able to go. But, thirty years ago, Herodotus could not have obtained as much knowledge of physical science as he picked up at Halicarnassus in any English public school.

Long before I had anything to do with the affairs of Eton, however, the Governing Body had provided the means of giving such instruction in physical science as it is needful for every decently-educated Englishman to possess. I hear that my name is sometimes peculiarly connected (in the genitive case) with certain new laboratories; and, if it is to go down to posterity at all, I would as soon it went in that association as any other, whether I have any claim to the left-handed compliment or not. But you must recollect that nothing which has been done, or is likely to be done, by the Governing Body, is the doing of this or that individual member; or has any other end than the deepening and widening of the scheme of Eton education, until, without parting with anything ancient that is of perennial value, it adds all that modern training which is indispensable to a comprehension of the conditions of modern life.—Macmillan's Magazine.

 
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MACHINES DRIVEN BY SOLAR RAYS.
By GASTON TISSANDIER.

OUR readers have already been informed[1] respecting the solar machines constructed by MM. Mouchot and Abel Pifre, in which the heat of the sun is employed, either directly or through the agency of steam generated directly by it, as the source of power, and of their successful application to certain purposes in Algeria. M. Pifre, who is an assistant to M. Mouchot in his engineering work in Algeria, has continued his experiments, and made some improvements in the machines, by which their operation has been rendered more effective. The principal improvement is in the form of the reflector, or insolator, by means of which the rays of the sun are concentrated upon the boiler or other object to be heated. M. Mouchot's reflector was in the form of a simple hollow cone, formed with a straight line of projection. M. Pifre bends the line of projection so as to give it three different inclinations, and thereby obtains for the surface of his mirror a form nearly like that of a paraboloid. An interesting experiment upon the possibility of adapting the apparatus of M. Pifre to a European sun

  1. "Popular Science Monthly," vol. xviii, p. 283, and vol. xviii, p. 432.