688 



Transactions of the Society. 



No. 18. Centimetre di- 

 vided on silver into 

 milimetres and tenths, 

 by William Gaertner 

 and Co. Bulloch stand 

 No. 2, Zeiss filar, 

 Bausch and Lomb 1 in. 

 prismatic illuminating 

 objective. 

 ldiv. = 0-1986^ 



No. 23. Micrometer on 

 glass, ruled by Prof. 

 J. H. Mulvey (Armour 

 Institute) to tenths 

 and hundredths mm. 

 Spencer stand, Leitz 

 filar, Leitz No. 3 objec- 

 tive. 



1 div. = 0-6823 n 



No. 24. Glass micrometer, 

 ruled byH. J. Grayson, 

 Melbourne. One milli- 

 metre divided into 

 hundredths, tenths and 

 quarters. Spencer 

 stand, Leitz filar, and 

 Leitz No. 5 objective. 

 ldiv. = 0-2085^ 



S3 

 Eg 



a; v 



r * 5 mm. 



1st 

 2nd 

 3rd 

 4th 

 5th 

 6th 

 7th 

 8th 

 9th 

 10th 



No. of 

 Div. of 

 Micro- 

 meter. 



div. 

 535 9 

 500-1 

 504-7 

 507-4 

 467-6 

 535-3 

 502-7 

 508-4 

 505-6 

 469-6 



Relative 

 Corrections. 



In Div. 

 of Micro- 

 meter. 



div. 

 -32-2 

 + 3-6 



Mean 



No. 1. Bausch and Lomb 

 micrometer, above de- 

 scribed. Spencer stand, 

 Zeiss filar, Spencer 4 

 mm. (^ in.) objective. 

 1 div. = 0-0388 /x 



Same scale and instru- 

 ments, except Leitz 

 No. 3 objective, 

 ldiv. =0-169 ix 



1st 



2nd 



3rd 



4th 



5th 



503-7 



144-5 

 144-8 

 144-4 

 144-3 

 144-6 



Mean \ 144-5 



1st 

 2nd 

 3rd 

 4th 

 5th 

 6th 

 7th 

 8th 

 9th 

 10th 



Mean 



tor, mm. 

 1st 

 2nd 

 3rd 

 4th 

 5th 



477- 

 477- 

 480- 

 478' 

 477' 

 480' 

 478' 

 480 

 477 

 478 



478-8 



260-4 

 260-6 

 265-0 

 245-2 

 259-2 



Mean 



1st 

 2nd 



258-1 



292-9 

 297-5 



Mean , 295-2 



- 1-0 



- 3-7 

 + 36-1 

 -31-6 

 + 1-0 



- 4-7 



- 1-9 

 -I-34-1 



0-0 

 0-3 



+ 0- 

 + 0' 

 - 



+ 



+ 



+ 

 + 



+ 



+ 

 + 



In 



Mikrons. 



- 2-3 



- 2-5 



- 6-9 

 + 12-9 



- 1-1 



+ 



2-3 

 2-3 



-6-4 

 +0-7 

 -0-2 

 -0-7 

 + 7-2 

 -6-3 

 +0-2 

 -0-9 

 -0-4 

 +6-8 



00 

 -0-2 

 +0-1 

 +0-1 

 -0-1 



+o 



+0 

 -0 

 +0 

 +0 

 -0 

 +0 

 -0 

 +0-2 

 0-0 



-0-1 



-o-i 



-0-3 



+ 0-5 

 0-0 



+0-4 

 -0-4 



Remarks 



This scale is in- 

 tended for the use 

 of schools, and 

 does not profess to 

 be of the highest 

 accuracy, having 

 been ruled auto- 

 matically without 

 applying correc- 

 tions. Lines too 

 coarse for high 

 powers, and in- 

 tended only for 

 relatively coarse 

 measurements. 

 Total length not 

 determined. 



Five readings on each 

 end of each space. 



Ten readings on each 

 end of each space. 



Record Book, page 34. 



Ten readings on each 

 space. Total length 

 not determined. 



Record Book, page 34, 



