Group of the Pleiades. 



249 



Relative Errors of the Single Spaces. — Concluded. 



Space. 



Error 

 of Space. 



Total 

 Error. 



Space. 



Error 

 of Space. 



Total 

 Error. 



Space. 



Error 

 of Space. 



Total 

 Error. 



300-301 

 301-302 

 302-303 

 303-304 

 304-305 



div. 

 + 1.6 



—3-i 



— 0.2 



+07 

 + 1.1 



div. 

 + 1.6 



—i-5 



—1-7 



— 1.0 



0.0 



305-306 

 306-307 

 307-308 

 308-309 

 309-310 



div. 

 +0.9 

 + 1.2 

 — O.9 

 + 0.5 



—1.6 



div. 

 +0.9 

 + 2.1 

 + 1.2 



+ 1-7 

 O.O 



310-31 1 

 311-312 

 312-313 

 3I3-3H 

 3K-3I5 



div. 

 +0.7 

 +O.I 

 —i-3 

 +2.3 

 —1.8 



div. 

 +0.7 

 +0.8 



— o-5 



+ 1.8 



0.0 



Space. 



Error 

 of Space. 



Total 

 Error. 



Space. 



Error 

 of Space. 



Total 

 Error. 



Space. 



Error 

 of Space. 



Total 

 Error. 



315-316 

 316-317 

 317-318 

 318-319 

 319-320 



div. 

 — 1.6 

 — 0.2 



+ i-3 

 —2.8 



+3-3 



div. 

 — 1.6 

 —1.8 

 —0.5 

 —3-3 

 0.0 



320-321 

 321-322 

 322-323 

 323-324 

 324-325 



div. 

 +3-9 

 —2.8 

 —1.8 

 —0.4 

 + 1.1 



div. 

 + 3-9 

 + 1.1 



— 1.1 

 0.0 



325-326 

 326-327 

 327-328 

 328-329 

 329-330 



div. 

 —1.6 

 + 2.9 



+ 2-5 

 —1.8 

 — 2.1 



div. 

 + 1.3 



+3-8 



+2.0 



0.0 









Space. Err° r 

 |of Space. 



Total 

 Error. 















330-331 

 331-332 

 332-333 

 333-334 

 334-335 



div. 

 —0.9 



—2.7 



+ i-5 



+2.4 



div. 

 —0.9 



-3-6 



— 2.1 



+0-3 

 O.O 









Professor Rogers finds that at 62°.o Fahrenheit 



1 average space of the Rutherfurd scale = 0.020859 inches. 



From the above observations he has computed a table of correc- 

 tions for every line of the scale. The corrections are expressed in 

 microns, and in the computation the relation already given, viz: 



1 micron = 5 div. of the microscope 

 has been used. The relation between the micron and the Ruther- 

 furd scale is : 



1 average space of scale == 529.9 microns. 

 I have therefore divided the corrections given by Professor Rogers 

 by 529.9, and thus obtained the following table of division error 

 corrections, which must be added to readings of the scale. These 

 corrections are expressed in terms of the average space as a unit ; 

 and will reduce the readings to what they would have been, if all 

 the spaces were exactly equal to the average space. 



