302 J. M. Silliman—Examination of the Bessemer Flame. 
magniiying power of six, and a tube containing the adjustable 
slit and lens for rendering the rays parallel; also a tube with 
a scale, which is placed at such an angle that it is reflected 
from the surface of the prism through the telescope to the eye ; 
it can be so adjusted as to appear along the upper edge of the 
spectrum. I was provided with Bunsen’s plates of spectra on 
a large scale, and in order to adapt them to the scale in my 
instrument, I took the spectrum of the sun and obtained 
Fraunhofer’s lines with great distinctness. Two characteristic 
lines in the solar spectrum were then noted, one of which 
appeared at 37° and the other at 117°, and a space measured 
equal to their distance apart as given on Bunsen’s scale. 
This was divided into eighty equal parts, and the division 
extended in both directions. By the application of this scale 
to Bunsen’s, [ found that the remainder of Fraunhofer’s lines 
in my instrument exactly coincided with their position on his 
plates. The correctness of the new scale was also proved by 
other coincidences. By moving the prism, Fraunhofer’s lines 
t 
about thirty feet from the flame, though I have stationed my- 
self at intermediate points between that and the flame; at one 
time sitting so close as to be almost scorched. Nearly all 
my observations were made at night and the lines obtained 
much better defined than when seen in diffused sunlight. 
The my observations was kept as follows :—Five 
columns were ruled, headed— 
| Degree. | olor. | Brightness.| Time. | Remarks. | 
Note was made of the dark bands as well as the bright ones, 
both of which were classed according to their distinctness, as 
very bright, bright, faint, and very faint. In the time-column 
was noted the number of minutes after the commencement of 
