; IMIOF. IIHJII I- I'ALLKSIMR AND MI?. HERBERT MOSS 



tin- datr. Tli.- second column gives the observed value of the effective height of the 

 |...t .-..liinm II. OOlWCted '>r scale error and temperature. The correction for the 



,litt;.ivn( C li-n-rtli 'HI ..f the hot and cold columns was always negligible in the first 



two sriics. and tin- value of </H is not given in the tables. In the third series this 

 correction Uraiiir appreciable, and a separate column is added giving the values of 

 III. Tin- third and fourth columns give the temperatures ti and t s of the cold and 

 hot columns, reduced to the gas scale. The fifth column gives the value of the 

 ditft-ivncf <>f lrvt-1 // in the gauge, corrected for errors of the standard invar scale, and 

 for ilitf'.TfiK'f of temperature between the gauge columns. These corrections seldom 

 eded O'OOl cm., the limit of accuracy of reading and the data for applying them 

 could not have conveniently been included in the tables. The value of h is not 

 corrected for the mean temperature of the column h itself, which is given under the 

 heading / in the next column. The seventh column contains the value of the 

 UpUMUn a(' 20) from 20 C. to t a in terms of the volume at 20 C., calculated 

 by formula (6), to the same order of accuracy as the values of//, namely, to one figure 

 U-vond the limit of accuracy of reading. The values of the expansion are not directly 

 comparable, because they include the small variations of t 2 . The last column is 

 accordingly added, giving the corresponding value of the mean coefficient 2o2 from 

 20 to t t in terms of the volume at 20 C. A variation of a tenth of a degree in t 2 

 should produce a variation of about 2 in the last figure of this coefficient, so that the 

 small variations of t t would seldom affect the last figure but one of the coefficient. 

 The differences shown in this column exhibit the accumulated effect of all the possible 

 errors of observation, including the effect of lag, to which many of the larger differences 

 appear to be due. Since most of the observations were purposely taken in pairs, as 

 explained above, in such a way as to exhibit this effect, with a view to detecting and 

 eliminating it, it is probable that the accuracy of the final means is not seriously 

 by this source of error. 



Series I. Observations, 20 C. to 187 C. 



