667315-1886-Verification-of-the-Unifilar-Magtometer-Elliott-Bro--No-55- — Page 2

i

符

THE HONGKONG GOVERNMENT GAZETTE, 29TH MAY, 1886.

I compared the deflection bar with the standard at Kew and found it correct. e following constants were determined:-

467

At the same time

W 62.63 grammes, 1 9.4214 centimeters, d 1.0006 centimeters.

The angular value of one scale division of the vibrating magnet = 110".66.

deflection apparatus 60".46.

""

77

"1

""

When the scale reading is above the middle of the scale, the correction to the circle reading is dditive, and when below it is subtractive.

The induction coefficient in C. G. S. Units adopted is μ 4.917 (Log. p = 0.6917) being the ean of the following determinations:-

Vertical induction: 1886, January 1, μ5.04

Horizontal induction: 1886, January 8, μ = 4.68 4.74

11

5,

5.07

9,

"}

19

37

"J

8, = 5.26

The value of 1 +

2μ

is

1.000 364 for r = 30 and 1.000 154 for r

40 centimeters.

3

Date.

The reduction to 0° is

This is the mean of the following determinations:-

1885, December 28,

0.000 260t+0.000 002 44 t2

Temperatures of testing.

Reduction.

10°, 25°, 40°

+0.000 241t +0.000 002 81 t*

""

1886, January

30, 11,

0, 20, 40

+0.000 254t+ 0.000 002 44 t2

>

5., 20, 35

+0.000 285t + 0.000 002 07 ť

This formula evidently depends to some extent upon the temperatures, at which the magnet is ested, as the coefficient of the cube of the temperature is not taken into account.

TABLE I.

Value of 86400

P 86400

1 sec.

0.00001 2 3

9

10

10 0.00012

TABLE II.

απ'

Value of

16

Semi-arc

Semi-arc at end of observation in scale divisions.

at commencement.

35d

80d

25d

20d

15d

40d

.00003

.00002

.00002

.00001

.00001

35

.00002

.00002

.00001

.00001

30

.00002

.00001

.00001

25

.00001

.00001