Geodetic Data Collection Techniques - Geodesy: Introduction to Geodetic Datum and Geodetic Systems - page 60

Fig. 2.20 Gravity
determination by the rise-
and-fall method

the distances from the two measuring positions to the peak of its motion. According
to (2.25), where l 0 ¼ 0, V 0 ¼ 0, we will obtain:

2
,

1
2 g

T 1
2

H 1 ¼

and

2
:

1
2 g

T 2
2

H 2 ¼

H is taken to denote the distance between the two positions, and hence yields:

" #

:

2 2

1
2 g

T 1
2

T 2
2

H ¼ H 1 H 2 ¼

After rearrangement, the equation for g becomes:

8H
T 1

g ¼

T 2 :

ð 2 : 28 Þ

Thus, it can be seen that to determine gravity using the rise-and-fall method
requires the determination of time intervals T 1 and T 2 of the object passing two
positions with a distance of H during its rise and fall.