Permanence of the Butherfurd Photographic Plates. 221 



Results of the Measures, Plate 18, Standards. 



y-coordinate. 

 Circle right 91 43 38, 43 36. 

 Circle left 43 46, 43 54. 



Date of Measures, 1895, Dec. 3 

 Temperature, 57.5, 64.0. 

 Runs * 



Desig. 



of 

 Star. 



Microm. Readings. 



Diflf. 



Mean 

 2 



Screw 



and Div. 



Error. 



Final 

 Reading. 



Obs'r. 



On 



Star. 



On Scale. 



Line 



94 

 94 

 94 

 94 



19 

 19 

 19 

 19 



Reading. 



A34, E 

 W 



19 E 

 W 



18 m, E 

 W 



20 E 

 W 



9.0145 

 9-5265 



9-0345 

 9-5205 



9.0125 



9-5190 

 9-0250 

 9-5330 



10.9805 



II-4915 

 10.9910 



11-4795 



9-3475 

 9-8265 

 9-3580 

 9-8445 



1.9660 

 1.9650 

 1-9565 

 1-9590 



0-3350 

 0.3075 

 0.3330 

 0.3115 



0.9828 

 0.9789 



0.1606 

 0.1611 



— 0.0007 

 — 0.0007 



+0.0006 

 -|-o.ooo6 



94.9821 

 94.9782 



19.1612 

 19.1617 



D. 

 D. 



D. 

 D. 



X-coordinate. 



O - II J II 



Circle right 181 43 44, 43 49. 

 Circle left 43 49, 43 35. 



Desig. 



of 

 Star. 



A34,E 

 W 



21 E 

 W 



i8m, E 

 W 



22 E 

 W 



Microm. Readings. 



On 



Star. 



9.0080 

 9.5270 

 9.0420 

 9-5195 



9-0325 

 9-5085 

 9.0165 

 9.5110 



On Scale. 



Line Reading. 



100 



lOI 



100 

 loi 



10.3225 

 11.0300 

 10.3645 

 11.0220 



9-8305 

 10.4760 



9.8095 

 10.4770 



Diff. 



Mean 

 2 



I.3145 



0.7044 



1.5030 

 1.3225 



0.7062 



1-5025 





0.7980 

 0.9675 

 0.7930 

 0.9660 



0.4414 

 0.4398 



Screw 



and Div. 



Error. 



+0.0001 

 0.0000 



+0.0003 

 +0.0003 



Final 

 Reading. 



29.2045 

 29.2062 



100.9417 

 100.9401 



Obs'r. 



* The runs were not observed, and the observations were reduced with the 

 assumed value E = + 0f0195. 



