Cor = correction for temperature of standard Vt3.
V = velocity of light.
T = value of one turn of screw. (Table, page 126.)

Substituting for d, its value or d×T×sec α (log sec α = .00008), and
for D its value 3972.46, and reducing to kilometers, the formulæ become--

dT
(3) tan φ = c′ ----; log c′ = .51607
r

n
(4) V = c ---; log c = .49670
φ

D and r are expressed in feet and d′ in millimeters.
Vt₃ fork makes 256.070 vibrations per second at 65° Fahr.
D = 3972.46 feet.
tan α = tangent of angle of inclination of plane of rotation = 0.02
in all but the last twelve observations, in which it was 0.015.
log c′ = .51607 (.51603 in last twelve observations.).
log c = .49670.

The electric fork makes ½(256.070 + B + cor.) vibrations per second,
and n is a multiple, submultiple, or simple ratio of this.




Observations.