[19] It would be an easy matter to amuse the reader with an account of these improvements. One of the most notable of them consists in covering the back of the reflectors with white paint, for the purpose of increasing the light of the circular field. This scheme is identically the same as if the author had proposed to improve the magnificent telescopes of Herschel, when rendered dark with a high magnifying power, by white-washing the interior of the tube.
[20] We request that the reader will take the trouble of comparing with the original the following translation of Baptista Porta’s description, which was published in London, and copied into all the foreign newspapers, etc. We hope the translator of it had no improper motive in altering the obvious meaning of the original; yet it is singular, that in the journal where this translation appeared, the specification of the patent was published under the title of Directions for making the Kaleidoscope, purporting to be an original communication to that journal, the name of the patentee, and the technical parts of the specification having been left out, apparently to promote the belief that there was no patent, and that every person might make them with impunity. The following is the translation alluded to:—
“In the following manner we may construct a mirror for seeing a multitude of objects on a plain surface. This kind of mirror, when constructed, is what is called polyphaton, that is to say, multiplying, for by opening and shutting, it shows twenty and more images of one single finger. If, therefore, you wish to prepare it, let two brazen or crystal rectangular mirrors be erected on the same base, and let the proportion of length be one and a half of the width, or any other proportion; and let each side for the whole of its length be so connected together that they may easily be shut and opened like a book, and that the angles may be varied, as they are usually constructed at Venice; for if you place one object opposite to the face of each, you will see several figures; and this in proportion as you shut it closer, and the angle shall be less. But, by opening, the objects will be reduced in number, and the more obtuse the angle under which you see it, the fewer objects will be seen. So if you exhibit your finger as the object, you will see nothing but fingers. The right fingers will be seen on the right side, and the left on the left side, which is contrary to the usual custom with looking-glasses; but this happens from the mutual reflexion and repulsion which produce a change of the images.”
[21] I have thrown the rest of the passage into a tabular form, that the reader may see, more readily, the effect produced by the variation of the angle.
[23] [See Chap. I. pp. 11, 12], where we have shown that Harris was not even acquainted with the way in which the last sector is formed by reflexion.
Transcriber’s Notes:
The cover image was created by the transcriber, and is in the public domain.
Antiquated spellings were not corrected.