182 



one set of readings for each temperature ; and in order to avoid as 

 much as possible the changes which may occur during the reading 

 off, it is well to reverse the order of observing the instruments, that 

 is, to read them alternately in the order one to six, and six to one. 



The following table contains the results of comparisons of six 

 thermometers, and will show the accuracy which may be obtained 

 by the method of comparison just described; it will also exhibit the 

 accordance in the indications of instruments graduated according to 

 Regnault's process. Each result is the mean of six comparisons. 

 No optical assistance was used in reading off the scales. The free- 

 zing-points of all the instruments were determined on the same day, 

 after the comparisons were made. 



Results of Compaynsons of various Thermometers, March 19, 1852. 



Standard Thermometers. 



Barrow, E.I.C., 

 s No. 4. 



Ne^vman 

 (Makerstoun). 



Troughton and 



Kew No. 4. 



Kew No. 14. 



Fastr^ 231 

 (Regnault). 



Tempe- 

 rature 

 from 

 mean of 

 stand- 

 ards. 



[Simms (Royal 

 Society). 



Ob- 

 served 

 tempe- 

 rature. 



Diff. 

 from 

 mean of 

 stand- 

 ards. 



Ob- 

 served 

 tempe- 

 rature. 



Diff. 

 from 

 mean of 

 stand- 

 ards. 



Ob- 

 served 

 tempe- 

 rature. 



Diff. 



from 

 mean of 

 stand- 

 ards. 



Ob- 



ser\"ed 

 tempe- 

 rature. 



Diff. 

 from 

 mean of 

 stand- 

 ards. 



Ob- 

 served 

 tempe- 

 rature. 



Diff. 

 from 

 mean of 

 stand- 

 ards. 



Ob- 

 served 

 tempe- 

 rature. 



Diff. 

 from 

 mean of 

 stand- 

 ards. 



o 







o 















32-00 



32-05 



+0-05 



32-05 



+ 0-05 



32-25 



+0-25 



38-69 



-0-02 



38-73 



+0-02 



38-72 



+0-01 



38-71 



38-91 



+0-20 



38-86 



+0-15 



38-96 



+0-25 



45-05 



+0-01 



45-03 



-0-01 



45-03 



-0-01 



45-04 



45-30 



+ 0-26 



45-18 



+ 0-14 



45-30 



+ 0-26 



49-96 



0-00 



49-97 



+ 0-01 



49-96 



000 



49-96 



50-34 



+0-38 



50-23 



+0-27 



50-23 



+ 0-27 



55-33 



-0-02 



55-35 



0-00 



55-37 



+ 0-02 



55-35 



55-87 



+0-52 



55-75 



+0-40 



55-62 



+ 0-27 



60-07 



-f 0-01 



60-06 



0-00 



60-05 



-0-01 



60-06 



60-65 



+0-59 



60-58 



+ 0-52 



60-34 



+0-28 



65-39 



-0-01 



65-39 



-0-01 



65-41 



+0-01 



65-40 



65-99 I+0-59 



66-03 



+0-63 



65-65 



+0-25 



69-93 



0-00 



69-92 



-0-01 



69-95 



+0-02 



69-93 



70-57 i + 0-64 



70-67 



+0-74 



70-22 



+ 0-29 



74-69 



0-00 



74-68 



-o-oi 



74-69 



0-00 



74-69 



75-39 i + 0-70 



75-54 



+0-85 



75-02 j+0-33 



80-08 



+0-02 



80-03 



-0-03 



80-06 



0-00 



80-06 



80-78 1+0-72 



81-00 



+0-94 



80-44 



+0-38 



85-30 



-0-01 



85-30 



-0-01 



85-33 



+0-02 



85-31 



86-10 1+0-79 



86-25 



+0-94 



85-75 



+0-44 



90-50 



0-00 



90-49 



-0-01 



90-51 



+ 0-01 



90-50 



91-36+0-86 



91-47 



+ 0-97 



90-87 



+0-37 



95-29 



+0-04 



95-23 



-002 



95-24 



-0-01 



95-25 



96-15 



+0-90 



96-32 



+ 1-07 



95-72 [+0-47 



101-78 



+ 0-01 



101-76 



-0-01 



101-77 



0-00 



101-77 



102-71 '+0-94 



103-04 



+ 1-27 



102-26 1+0-49 



109-21 



+ 0-05 



109-11 



-0-05 



109-15 



-0-01 



109-16 

 212-00 



110-08 



+ 0-92 



110-62 



+ 1-46 



109-58 

 212-47 



+ 0-42 

 + 0-47 



The thermometers " Kew No. 4 " and Kew No. 14," were 

 graduated on the stems by myself with arbitrary scales : the bulb of 

 No. 4 is spherical, and is about f inch diameter; that of No. 14 is 

 cylindrical, |- inch long and \ inch diameter, and very sensitive. 

 " Fastre No. 231 (Regnault) " is a standard by Fastre of Paris, also 

 graduated on the stem with an arbitrary scale according to Reg- 

 nault's process. This instrument was examined and approved by 

 M. Regnault ; the determination by him of the scale coefficient 

 agreed closely with that afterwards made at Kew. The bulb is 

 cylindrical, about \\ inch long and \ inch diameter. " Barrow, 

 E.I.C., S 7, No. 4," is one of a number of thermometers made for 

 the East India Company and sent to Kew for examination. Its scale 



