Franklin £natitute. !209

KALICHROMATRY,

BY PROF. ALBERT R. LEEDS.

SoME very pleasing effects may be obtained by superimposing the spectra from two bisulphide of carbon prisms upon the screen with two lanterns, arranged, as is usual, for dissolving views; one is to be pointed upward, through an angle of 64 ° 16 t, the angle of minimum divergence--for a prism of 60 ° refracting angle--and the other is to be turned away from the screen, through the same number of degrees. Before the objective of the first, a prism is to be held, with its refracting angle ~ipwards; before that of the second, another prism, with its refracting angle vertical. Glass plates, with a coating of blackened collodion or varnish having been prepared, the sur- face may be scratched away, so as to leave the glasses with one, two, or three horizontal bars, or the upper and lower quarter seg- ments of a circle. These will be brought to a focus by Lantern No. 1, and will produce one, two, or three horizontal spectra, as the ease may~oe. Corresponding glasses are to be prepared for Lan- tern No. 2, but with the bars vertical, or not differing therefrom by more than 45 ° . The width of the line should not exceed one-eighth of an inch. In this way the screen may be covered by a cross, or a grating of spectra, giving finely-contrasted tints, or circles, &c., may b e formed. These expedients were resorted to, because the diacausties produced by holding rods of glass, &e., in the path of a

single decomposed beam were not satisfactory or brilliant.

Prooeedings of the Stated Monthly Meeting, ~anuary 1Bth, 1868.

TKE meeting was called to order with the President, Mr. J. ~r~ughan Merrick, in the chair,

The minutes of the-Board of Managers were reported by the Actuary.

VoL. LV. 27

210 BibliograThical Notices.

Donations to the Library were received from the Society of Arts, London, and the Association for the Prevention of Steam Boiler Explosions, Manchester, England; ]a Socidt6 d'encouragement pour l'Industrie nationalle, l'Acdemie des Sciences, Paris, and ]a Socidt6 Industrielle, l~iulhouse, France; der K. K. Geologischen, Iteichanstalt, ¥ienna, Austria; Major L. A. Huguet-Latour, Mon- txeal, Canada; Hon. Chas. O'Neill, M. C. ; Prof. B. Pierce, Super- intendent Coast Survey, The U. S. Observatory, Washington, D. C. ; The Water Commissioners of Jersey City, N. J. ; and from Messrs. S. S. White, Henry Vezin, and J. M. Maich, Philadelphia.

The Annual Report of the Board of Managers was then read. The result of the election on that day was announced, and the.

following gentlemen were declared elected as officers of the ensuing year : -

For President, Mr. J. ¥ . Merrick, for one yeax; for Vice-President, Prof. It. E. Rogers, for three years; for Treasurer, Mr. Frederick Fra. ley, for one year; for Secretary, Prof. t~enry Morton, for one year ; for Auditor, Mr. Win. Biddle, for three years ; for Board of Managers, William B. Le Yah, Percival Roberts, Jacob Naylor, Samuel Sartain, 0. li . Wilson, Charles Bullock, E. Longstreth, Enoch Lewis, for three years; Jacob G. Neaffie, for two years; J. It. Linville, for one year.

The paper announced for" the evening, on Pneumatic Piles, was then read by the lion. W. J. McAlpine, C. E.

The Secretary's report on Novelties in Science and the Mechanic Arts, was read, at the conclus~n of which the meeting, on motion, adjourned.

HENRY MORTON, Secretary.

.Leaf Prints ; or, Glimpses at Photography. By Charles F. Uimes, Ph.D., Professor of Natural Science, Dickinson College, Carlisle, Pc. Philadelphia : Bennerman & Wilson, 1868. This little book is one that attracts attention immediately by its

very beautiful outward form, and gratifies equally by its literary and scientific worth. Professor I=Iimes writes like a scholar and artist. He gives an interesting preface and an admirable introduc- tion to his book, which all may read with pleasure and profit, and