|Instrument||:||Station Pointer (Protractor)|
|Manufacturer||:||Warren Knight Co|
|Country of origin||:||U.S.A.|
I've obtained this instrument in 1996 together with the Kelvin Hughes station pointer in my collection. The instrument is used for coastal navigation using a sextant and was invented in 1801 by Joseph Huddart, a U.S. naval captain. This instrument, also referred to as a three-arm protractor, is composed of a circular scale connected to three arms. The centre arm is fixed, while the outer two can be adjusted to an angle previously measured with a sextant.
In coastal navigation the vessel's coordinates can be established by measuring two horizontal angles between three coastal objects. After setting the legs of the station pointer to these angles (adjustment is done with two verniers) it can be laid on a map showing the same objects. With the legs running over the objects on the map, the center of the instrument will be your position in it.
This protractor has Serial Number 7700, and was manufactured in 1942. Warren-Knight made hundreds of them during WWII. The number 70 on the back of the instrument (according to one of the instrument makers over there for almost 60 years) is probably the number of the instrument from the "Lot" or group of instruments made at one time. The number stamped on the back would help the instrument makers keep track of what parts went with which instrument as they were being made as the parts were all hand fitted due to the accuracy that had to be achieved for these instruments [RM].
This model protractor is still produced on request by Warren-Knight as Model #24-1175L. The mirrored version (able to close the right hand legs) is manufactured as Model #24-1175R.
[RM]: Rick Marron, Warren-Knight Instrument Company, Philadelphia, USA.