Instruments \ Gravity \ 

Description:

Cast aluminum container 58 cm W; 52.5 cm H; 34 cm Dia; has carrying handle at each side. Two pendulums made of quartz, each 32.3 cm L; 5.5 cm W and 6.4 cm Thick.

Item 07A-G is a Gulf Pendulum apparatus; the pendulums are inside. On the one end is a pressure gauge to indicate the air pressure inside; on the side is the evacuation port for evacuating the air so that you can get to a low vacuum. On the side near the top is a window through which the light entered and made its circuit around the various pendulum paths and came back out to a photographic recorder.

The photographic camera is #07b and recorded on 35 mm paper. Just below the window that carries the photographic elements are the clamping mechanisms. The handles for the apparatus are placed in such a position that when it is unclamped the machine cannot be picked up by its handles. When it is clamped the handles slide into sockets and it can be picked up. #07b are a pair of the Gulf Pendulums that would presummably fit in the case The pendulums are minimum length, fused quartz pendulums. The main bar of the pendulum is one piece of fused quartz and the knife edge is a second piece of fused quartz that is cemented into the first so that in effect, it is almost one solid piece of fused quartz. A pendulum period vs length changes in a semi-parabolic fashion and by making the pendulum at the minimum length at the peak in the curve it minimizes the change in the length due to temperature or wear of the knife edge. This is the reason they were made as minimum length pendulums.

The flats on the front of the pendulum are the mirror surfaces for the pendulum and are flat to a tenth of a wave length of light. The pendulums are hung on a flat when a mechanism for lowering them are used in the case, and the flat on which the knife edge rests is also flat to a tenth of a wave length of light. One of the one tenth wave length flats in #07c is a spare for one of the pendulum apparatus.

There are a couple of templates that were used in reading the records for amplitude or period measurements. #06 has on the outside a heating element which is in a covering which is wrapped around the external part of the case, and a second covering covers that which is insulation for the whole operation. So the pendulums can be temperature controlled to the desired level.

ITEM 07e DUMMY PENDULUMS - Made in 1937

These were made to do test operations with the Gulf Pendulum Apparatus so that it was not necessary to use the good quartz pendulums when making tests. They were not to be used at all for actual measurement, just for testing purposes.

ITEM 07 F AND G

These are the base plates for the Gulf Pendulums. The three holes in the corner were for wooden stakes which were driven into the ground, then the aluminum platform with the three holes in it were attached to the wooden stakes and clamped on to it solidly, then the 7f unit was placed on top and the Gulf Pendulum went on the 3 pads on Item 7f. This was supposed to provide a good stable platform for them in any kind of soil condition.