1836 Solar Compass Patent

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***Handwritten Patent text transcribed to the best of our abilities***


William A. Burt,   Mount Vernon, Territory of Michigan

                                    (Patented February 25, 1836)

The Schedule referred to in these Letters Patent and making

part of the same, containing a description in the words of the said

William A. Burt himself of his improvement in the instrument for

determining the variation of the Needle, the true meridian and 

the apparent time.

                                             Be it known that I William A. Burt of Mount Vernon, Macomb County, Territory of Michigan have made an improvement, being an instrument for determining the variation of the needle, the true meridian, and the apparent time, which is described as follows reference being had to the annexed drawing of the same making part of this specification. This instrument is supposed to be attached to a circumferentor or some similar instrument having a level in it.  The arc (a) is graduated to half degrees and works in a clamp (p) with a nonius (g) and cleats the arc (b) to the latitude of the place and is secured by the clamp screw (r), which arc is also graduated to half degrees.  Upon the arc (b) is fixed a movable limb (c) having an opening (e) for a nonius, which limb turns on the center (d) and moves parallel on the arc (b).  Upon the movable limb (c) is fixed an arc (o) for bringing the arm (f) to the sun & moon declination.  Upon the moveable limb (c) is also fixed the support (g) upon which rests the arm (f) bearing the convex lens (i) for converging the rays of the sun and throwing , and throwing them upon the plate (k) which is marked with three lines, and upon the middle one of which the true meridian is shown.  There is also a dark glass (w) placed over the convex lens.    Operation:  First place the Instrument level,

locate the arc (b) to the latitude of the place and clamp it adjust the arm (f) to the sun or moon declination and also clamp it, move the limb (c) to the hour of the day marked on the limb (b) which will throw the sun's image upon the plate (k) and when brought upon the centre line, will show the true meridian.  The difference between this and that shown by the needle will be the variation, and the nonius in the limb (c) will show the apparent time. ~ What I claim as my invention is the before described instrument for showing the variation of the needle by giving the true meridian, also the apparent time.


J. H. Vanclece (?)                                    William A. Burt

Wm. L. Elliot

                                         Patented 25th of February 1836


Exd   (?)      ( Rec'd & Recorded December 31, 1838)



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