7 
; 
TRANSACTIONS OF SECTION A. 937 
F. Galton, Mr. T. Cooke, and himself. Stating that the verification of the instru- 
‘ments comprises four stages; viz. Examination of (1) telescopes, (2) mirrors, (3) 
dark shades, and (4) errors of eccentricity and graduation of the arc, he detailed 
the various operations conducted in each stage, and finally classified the frequency 
-of the various defects as determined from upwards of 169 instruments verified at 
the Observatory during the past year:—15 per cent. were defective in stage 2, 
-5 per cent. in stage 3, and 10 per cent. in stage 4. An analysis of all the instru- 
ments under test (4) showed that 20 per cent. had errors amounting to 30’, 30 per 
cent. amounting to 60’, 25 per cent. amounting to 120”, and 7 per cent. amounting 
‘to 180”; whilst only 2 per cent. fell below 20”, and were practically perfect in 
‘their gradation. 
6. On the Behaviour of First-class Watches whilst undergoing tests in the 
Rating Department of the Kew Observatory, Richmond, Surrey. By 
G. M. Wurertez, B.Sc., F.R.A.S. 
The watch-rating department of the Kew Observatory, Richmond, Surrey, has 
been established in order to provide makers and the public with certificates of the 
accuracy of the performance of good watches. The conditions of the trials 
‘adopted for three classes, A, B, C, for watches of different qualities, which are 
detailed below, are similar to those in use at the Geneva and Yale Observa- 
tories. 
The following table will indicate the nature of the trials to which the certificates 
refer, the variation of rate being determined daily :— 
For Certificate of Class 
Position of Watch during test 
A B Cc 
Vertical, with pendant up . é : 10 days l4days | 8 days 
” ” ” right o) * 5 ” mc _ 
” ” ” left 5 ” arr | Ty 
Horizontal, with dial up . E Ail # aes 14days | 8 days 
2 aa itt ttddwnl' a: - 3 ba . — | — 
* at temp. 85° F. ones 1 day i 
” ” 35° BF. g 5 ” 1 ” ah 
Not rated (intermediate days) Bay AL as —— 
Total duration of test . - - 45 days | 31 days 16 days 
The results derived from of recent trials of 1384 watches were given in a tabu- 
lated form, and were contrasted with similar numbers derived from foreign trials. 
The number of failures to obtain certificates were— 
14 per cent. for variation of rate 
8» ” ” due to position 
05 ,, » imperfect temperature compensation 
3 4, 4y__ other causes. 
‘7. On a recent Improvement in the Construction of Instruments graduated 
upon Glass. By G. M. Wuippie, B.Sc., F.R.A.S. 
The very clever invention of Messrs. Negretti & Zambra some years ago of 
running a slip of white enamel in the glass at the back of the bore of the tube of 
-a thermometer has been most highly valued by scientists. I now submit to the 
notice of members of the Association a number of thermometers, eudiometers, 
graduated measures, &c., in which a valuable extension of the use of enamel has 
heen carried out by Mr. Jas. J. Hicks, of 8 Hatton Garden, London. 
