Notices of Books. 
261 
1878.: 
into such recondite properties as those referring to the centre of 
gravity. More plates and less letter-press would have made this 
book more useful to the designer and certainly not less useful to 
the student. 
Photographed Spectra . Printed by the Autotype Process. By 
G. Rand Capron, F.R.A.S. London : E. and F. N. Spon. 
1877. 
This work contains no less than one hundred and thirty-six 
photographs of metallic and gaseous spectra, accompanied by a 
full description both of the conditions of each experiment and of 
the spectra themselves. The spectra range from about the line b 
to beyond H 2 in the violet, and the method of reproduction 
enables much more of the spedtrum in the direction of the violet 
to be delineated than is ordinarily found in representations of 
spectra. Each spectrum in its photographed form was found to 
present a readily recognised individuality, and the author was 
thus induced to imagine that the permanent reproduction of them 
might furnish a handy bookVof reference to spectroscopists. 
The spectroscope employed was by Browning, and was spe- 
cially constructed for auroral observations. The prism was an 
inch aperture compound, easily dividing the D lines, and the 
collimator carried a 14-inch lens of 6 inches focus. The camera 
was in immediate connection with the spectroscope, and the 
images were taken upon collodion wet plates, 44 by 34 inches. 
The metallic spectra were produced by the spark, and also by 
the electric arc. The former was obtained from a large Ruhm- 
korff coil giving a 2-inch spark, and the latter by forty pint 
Grove cells. The width of the slit averaged 0*003 inch. Seve- 
ral attempts were made to obtain photographs of the red end of 
the spectrum. A full explanation of the various photographs is 
given. All the elements, metallic and non-metallic, with a few 
exceptions which could not be photographed, are given. 
The work will be found of great service to the spectroscopist, 
and of interest even to those who do not work practically. 
Miscellaneous Papers connected with Physical Science. By 
Humphry Lloyd, D.D., D.C.L., Provost of Trinity College, 
Dublin. London : Longmans. 1877. 
This work contains a reprint of twenty-three papers, reprinted 
from the “ Transactions of the Royal Irish Academy,” the 
“ Reports of the British Association for the Advancement of 
Science,” and elsewhere. Four of these relate to Optics, and 
