484 PROFESSOR W. N. HARTLEY AND mi H. RA:\IAGE OX THE SPECTRA 
1) e noticed that we have to observe the “ blow” in different stages, and also the “ over¬ 
blow ” ; it is desirable that some general account of the photographs which were taken 
at different times be recorded, and that the details of some of the sj)ectra be given 
when of particular interest. 
In all some twenty-six plates were developed, some few of which were failures 
owing to circumstances already described, hut Nos. 4, 14, 15, 17, 23, and 26 were 
particularly valuable. A full account of all the details of the operations witnessed 
witli a precise description of the spectra on each plate being considered unnecessary, 
the particulars of No. 14 oidy are here given, followed by a summary of all the 
spectra on the other plates. In making the observations it was found necessary at 
first for one person to attend to the spectrograph, a second to watch the “ blow” and 
oljserve the flame with a direct-vision hand spectroscope, and obtain a record of what 
was taking place with the Anschutz camera, while the third recorded the time and 
entered the notes and remarks made to him. Subsequently, two observers were 
engaged—one in managing the spectrograph, the other in entering all details in the 
note-book. When a succession of thirteen spectra are photographed in 15 minutes, 
there is ljut little opportunity for entering notes of every detail. The omission of 
these details greatly diminishes the value of the observations; on the other hand, 
photographs of the operations greaffly enhance their vahie. 
Plate No. 14. A series of six spectra which are in very sharply defined focus in 
the green. The following table gives the intensities of the lines and bands in the 
different sj^ectra from 1. to VL, with the period of exposure in each case, the periods 
being consecutive. 
Note .—There were 140 spectra on the twenty-six plates. The plates were 
numbered consecutively and the spectra on each plate were numbered in the order 
of their exposure. The references in the text to numbered plates relate to the 
2 ) JiOtographs and not to illustrations, which have been omitted. 
