ApEnrY & Carson—The Rowland Spectrometer, R. U. I. 718 
Fig. 1 shows this structure in section, with the rail, carriage, and 
grating indicated in position inside. 
D 
a Fig.1. 
NS 
K, 
cH ——————— R 
a 
M represents a cast-iron standard. 
B 
QOH ft @ 
34 the beam 12” by 3”. 
#8 the saddle. 
“3 the rail. 
5 sheeting of 2” cedar wood. 
55 framed top fastened to © and supported by brackets. 
The panels in this are represented by movable 
lids (D). 
AA are pieces secured, one to B and the other to c, and grooved 
for the reception of sliding doors, each about 2 feet wide, 
by means of a series of which the side of the rectangular 
box could be closed in from either end, making the whole 
completely light-tight. This construction was necessary, 
inasmuch as the girder passed out through this side, and 
at a varying angle, and different position, with every 
movement of the grating carriage along u, and with the 
corresponding movement of the camera along the other 
rail H’. 
3G 2 
