LABORATORY OPTICAL PYROMETER 
79 
turning the knurled head F. This turning actuates the screw W 
in the nut U which is attached to the center-post supporting the 
table T. With these horizontal and vertical motions it is possible 
to set the kink of the pyrometer-lamp filament in the optical axis 
of the instrument. 
The bed of the pyrometer is made of a piece of angleiron 2 
inches wide by 3 inches high by 8/^ feet long. The top and back 
surfaces (in the picture) are machined. A channel running the 
full length of the bed at a distance of 3/16 inch from the top, fur- 
nishes the place for attaching the hook-clamps, like B oi figure 7, 
which hold the lens and telescope standards in position. The clamp 
B is so constructed that, when the thumbscrew is tightened, the 
clamp not only pulls downward but also exerts a horizontal force 
which brings the guides, attached to the base of the standard, 
against the machined surface of the bed; this keeps the parts in 
alignment. The pyrometer-lamp standard is secured by means of 
suitable spring-fingers. 
To the bed are attached two studs which slide in slots in the top 
of the piece Q, Fig. 8, thus allowing the bed to slide parallel to 
itself. This motion is produced by turning the knurled hand-wheel 
/, Fig. 7, It permits the operator to focus the pyrometer on the 
background while he is looking through the telescope. The bed 
may be locked in place by tightening the thumb-nuts K. With the 
forked rod G the observer may make the vertical and horizontal 
adjustments of the pyrometer-lamp while he views the filament 
through the telescope. This rod G makes the aligning of the parts 
a simple operation. 
The post L supports the bed of the pyrometer. It is made of a 
piece of heavy iron pipe 2Vk inches in diameter which has square 
threads of ^ cm. pitch on the outside. By turning the nut M the 
bed may be raised or lowered, the maximum range of the motion 
being 18 inches. The nut may be locked in position by screwing in 
the handle, thus permitting rotation of the bed about a vertical axis 
without there being any danger of having the post turn in the nut. 
From figure 7 it is also seen that the bed may be tilted so that the 
observer may view the backgrounds either up or down at an angle. 
These adjustments give the instrument the flexibility which is ne- 
cessary for general laboratory work. The tripod base is very rigid 
and stable ; it is made of one-inch angleiron bolted to the two cast- 
iron guides through which the post L. passes. 
The motor with the sectored disc attached is shown at C, figure 
7. The motor is supported by a laboratory stand which at no 
