The Photographic Atlas of the Normal Spectrum. London: William Wesley & Son. 1894

London: William Wesley & Son, 1894. 1st Edition. FIRST EDITION. EXCEPTIONALLY SCARCE. In the late 19th century, George Cornish Sutton Higgs, a British watchmaker and optician proficient in the sciences, built an extraordinary spectrograph and employed it to greatly advance the application of photography to the study of solar spectra. The result of that work is offered here -- "one of the best atlases of the solar spectrum then produced" (Biographical Encyclopedia of Astronomers, 505).  

Higgs formulated no new theories to explain the natural world, he did use his skill in optics to "construct one of the finest solar spectrographs then in existence"; he then used that invention to follow "in the footsteps of others, [gradually working to refine] their techniques with greater care and precision" (ibid, 506). "

Higgs conducted his studies in a room of his small suburban house, using homemade apparatus. The accuracy of his line determinations and quality of his photographs were praised by leading British, Continental, and American astronomers and physicists (ibid).  

The heart of Higgs's spectrograph was a concave grating "mounted on one side of a circular table, ten feet two inches in diameter" (Payne, Astronomy and Astrophysics, Volume 9, 379). "The light enters from the right into the slit, is guided towards the grating in the back and from there onto the photographic plate in the box at the far left. Moving the slit along the big semicircle by means of an intricate pulley system causes different orders of the spectrum to fall onto the photographic plate. The path of the light, fully enclosed in card boxes, shields the plate from stray light" (Hentschel, Mapping the Spectrum: Techniques of Visual Representation in Research, 240).  

Higgs was chiefly interested in photographically recording the Sun's spectrum at different solar elevations, and under various weather conditions, to investigate the effects of atmospheric absorption. He designed his own induction coil for producing comparison spectra and perfected methods of sensitizing photographic plates, using the bisulphite compounds of alizarine blue and coeruline to reduce exposure times. In Higgs's day, the red end of the spectrum was notoriously difficult to photograph, due to the relative insensitivity of plates to the longer wavelengths. After much experimentation, Higgs was able to obtain plates with all of the definition normally associated with the violet end of the spectrum (ibid) "[Higgs] also perfected methods of eliminating visible grain from the enlargements of his spectral photographs" (Biographical, 506).

In the 1880s, Higgs began publishing his work on solar spectroscopy in leading scientific journals; in the 1890s, his work was complete enough that he published two editions of his Photographic Atlas of the Normal Solar Spectrum, this being the first edition.  

Additionally, Higgs "made a determination of the Sun's rotation period from spectroscopic observations, [showing] that by superimposing photographs of spectra taken from the eastern and western limbs, there was a slight displacement due to the Doppler effect, while the atmospheric absorption lines were unchanged. Some of these plates illustrated the first edition of Higgs's Atlas" (ibid).  

Higgs's accomplishment was praised throughout the scientific community. After carefully comparing two other photographic maps of the solar spectrum, one by Rowland and one by Rutherford, to those of Higgs, a contemporary expressed his admiration as follows:  

"The most striking feature of these [photographs], at first sight, is the extreme clearness with which every line stands out on the bright background, nothing hazy or obscure, the whole a perfect marvel of distinctness and sharpness of definition. All must admire the fine solar spectrum [...] by Professor L. M. Rutherford; and yet viewing this grand work, and then turning to the enlargements of Mr. Higgs, is like looking at the delicate outlines of a fine public edifice first through a November fog, and then in the brilliant sunshine of a clear spring morning" (Hentschel, 240).  

Higgs "achieved this ‘marvel of distinctness'... with a trick that helped him eliminate the granular structure of the silver in the original negatives. During exposure of the print, he purportedly moved the photographic plate parallel to the spectral lines, or else inserted a cylindrical lens in front of the enlarging lens. The effect of either method was to stretch out the lines and smooth out the grain in the background in a manner not unlike modern picture-enhancement techniques" (ibid, 240). CONDITION & DETAILS: London: William Wesley & Son. 4to. 9.5 by 4.25 inches (238 x 106mm). Small portfolio clamshell case with rubbing and scuffing at the edge tips and spine; bound in three-quarter calf over brown cloth; gilt-lettered on the front board. Within the case are 37 (of 38) spectrum photographs mounted on card stock, most depicting two ‘rows' per card, some also with four rows. As well, the portfolio is complete save for the absence of the one plate. Every photograph is in near-fine to fine condition.