PT Boat Forum


Moderated by: Dick, Jeff D

The PT Boat Forum ª PT Boats of WWII ª  PT Boats - General

Page: 1 of 1

Back to Topic Index Page 185 | Replies: 0

 Author  Topic: Hand held Observer Compass
Donald Shannon

Full Member
  

    
Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Donald Shannon  Posted on: Apr 30, 2009 - 2:11pm
I have printed a copy of the Observer Compass Instructions for easy reading see below. The image I posted of the instruction sheet just prior to this posting is not to clear.

Also some research info about the manufacturer at the bottom of this message.

Don Shannon PT Museum Battleship Cove


Observer Compass
Instructions for use and care
The OBSERVER Compass is a precision built instrument designed especially for obtaining distant shore bearings. The magnetic element and compass card are especially dead beat so that any unsteady motion of the ship transmitted to hand or compass will not disturb or interfere with its accuracy. Construction of the compass will not disturb of interfere with its accuracy. Construction of the compass and flashlight is entirely of brass of bronze so that there is no local magnetic disturbance. Don not attempt to use the OBSERVER Compass close to iron of steel fittings.

The hinged prism mounting is rigidly made so that the prism cannon be put out of alignment and change its focal length. Should the image in the prism become indistinct it is probably doe to dirt or water lodged between the prism and its bracket. To clean the prism, simply remove the screw from the chromium V piece and the bracket, clean the prism, and replace it. Make sure the alignment is correct before tightening the screw.

The compass bowl is equipped with an expansion to take care of contraction and expansion of the liquid and there is also a very large and capable bubble trap. As the compass is filled with a high-grade aircraft compass oil, it sometimes develops a bubble do to cold weather. Should this occur it is only necessary to tip the compass upside down and then level it slowly. This will put the bubble in behind the bubble trap where it will not be visible nor disturb the action of the compass card.

Care should be taken when removing and replacing the instrument in the carrying case. This case is designed to protect the prism and remove the possibility of vibration reaching the jewel and pivot. it is recommended that the carrying case and compass be stowed in a flat or horizontal position. this prevents wear on the jewel and pivot.

Should it be necessary to insert a new bulb in the flashlight, first remove the batteries, then unscrew the flashlight tube. the bulb may be replace in its reflector. if the occasion should arise where a spare complete flashlight is needed, simply unscrew the two small screws on one side and the two legs on the other side of the compass. Use only non-magnetic batteries.

To use OBSERVER Compass, it is simply necessary to hold it at eye level (at a convenient distance from the eye), and get the object on the prism at the same time, holding the Lubber line in line with the chromium V sight. The compass should be held approximately level when observing these bearings.

The compass itself may be used as a spare or tell tale by fixing its carrying case to a vertical bulk head. With the compass in the case, it is simply necessary to turn the flashlight on and read it.

The length of the compass is 91/2" overall and its outside diameter is 3 1/2". the carrying case is of mahogany, 11"long, 4 1/2" deepand 4" wide.
C. G. Conn, LTD.
Elkhart, Indiana
Continued on next page:
Continued from previous page:

Additional information researched about the manufacturer of the compass:

C.G. Conn Ltd., sometimes called Conn Instruments or commonly just Conn, was a United States manufacturer of musical instruments, especially brass instruments.

M. Low New York, New York a manufacturer of Nautical instruments such as compasses and clocks.


Donald Shannon

Total Posts: 47 | Joined: Apr 24, 2009 - 10:07am | IP Logged


Lock Topic

 

Forum Legend

New Member

Reply to topic

More than 25 posts | Full Member

Reply to topic with quoted message

More than 50 posts | Advanced Member

Edit Message

More than 150 posts | MASTER

View profile

More than 300 posts | TOP BOSS

Email member