. Carnegie Institution of Washington publication. . Fig. i. cross-hair in such cases is out of the question, for the field is much too dim to render it visible, while every attempt to illuminate it from the side would flood the eye-piece with light sufficient to quench that under observation. The instrument used in most of our observations was the spectropho- tometer of Lummer and Brodhun. In many of our earlier measurements the ocular lenses in the eye-piece were used, the eye being focused upon the aperture in the eye-piece and not upon the face of the prism. By means of metal screens attach
Image details
Contributor:
Book Worm / Alamy Stock PhotoImage ID:
RFT6T2File size:
7.2 MB (91 KB Compressed download)Releases:
Model - no | Property - noDo I need a release?Dimensions:
1201 x 2082 px | 20.3 x 35.3 cm | 8 x 13.9 inches | 150dpiMore information:
This image is a public domain image, which means either that copyright has expired in the image or the copyright holder has waived their copyright. Alamy charges you a fee for access to the high resolution copy of the image.
This image could have imperfections as it’s either historical or reportage.
. Carnegie Institution of Washington publication. . Fig. i. cross-hair in such cases is out of the question, for the field is much too dim to render it visible, while every attempt to illuminate it from the side would flood the eye-piece with light sufficient to quench that under observation. The instrument used in most of our observations was the spectropho- tometer of Lummer and Brodhun. In many of our earlier measurements the ocular lenses in the eye-piece were used, the eye being focused upon the aperture in the eye-piece and not upon the face of the prism. By means of metal screens attached to the collimator slits of the instrument the length of slit was regulated so as to avoid overlapping of the spectral images and to give two contiguous spectra in the field of view. One loses in this way the advantage of the method of contrast, but the brightness of the field is greatly increased. Later on the contrast field was employed because it was found to be less fatiguing to the eye and on the whole more accurate. Since in most cases it was desired to employ monochromatic light for the excita- tion of fluorescence, the spectrophotometer was employed in connection with a large spectrometer, as shown in Fig. i. The eye-piece and slit of the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Carnegie Institution of Washington. Washington, Carnegie Institution of Washington