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I would like to propose a small craft technique for the use of two
slide rules in solving an altitude of the sun by formula:

Hc = INV SIN of COS lat COS dec COS t +/- SIN lat SIN dec

A.   Predetermine product of SIN assumed nearest whole latitude and
SIN declination for nearest hour (commit to memory or recorded on
paper). This product should be good for an hour of sun CN.
(declination changing slowly)

Slide Rule #1

Preset to the product of COS assumed nearest whole latitude and COS
declination for nearest whole hour of UT/GMT. This preset should be
good for an hour of sun CN also due to the slow change of declination.
The total COS product of the equation can be performed without further
movement of the slide for an hour of selected assumed longitude
meridian angles.

B.   Sum predetermined SIN product with the COS  product of slide rule
#1

Slide Rule #2

To be  used to determine the INV SIN of sum to find Hc (20" slide rule
with magnifier recommended for best results)

Slide rule #1 remains preset as before which leaves slide rule #2
available for solving azimuth.



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