34 REPORT — 1900. 



of observations to be of value for the general discussion of results. To 

 show the nature of the records, and the working of the apparatus, a 

 sample record sheet for August 21, 22, 1900, including a zero test and two 

 comparisons with mercury thermometers, which were read simultaneously 

 at the two stations by separate observers, is given herewith. (Plate I.) 



The zero line on the chart was obtained by placing the thermometers 

 at the two stations in melting ice simultaneously, and allowing them to 

 remain for about an hour at this temperature. The differences between 

 the simultaneous readings of the mercury thermometers at the two stations 

 were plotted from this zero line, and show a very satisfactory agreement 

 with the differential platinum thermometers, considering the continual 

 variations of temperature and the difference in sensibility of the two 

 instruments. The direction of the wind and the velocity in miles per 

 hour are recorded by instruments placed on the summit and connected by 

 lines to the electrical recording apparatus in the College Observatory at 

 the lower station. The record for August 21, 22 exhibits a complete 

 revolution in the direction of the wind from N.W. through E. and S. and 

 back to N.W. These changes in the direction of the wind frequently 

 appear to be related to the changes in the difference of temperature. The 

 amount of sunshine in tenths per hour recorded at the College Observa- 

 tory is also marked on the charts, and the general weather conditions 

 prevailing. 



The apparatus as at present arranged gives admirable results in fair 

 weather, but it has been found impossible to preserve the insulation of the 

 line during rain. This has steadily deteriorated since its erection, and 

 the results cannot now be relied on when the rainfall is considerable, or 

 .for short periods after. This is unfortunate, as it would be interesting to 

 study the changes of temperature occurring with the onset of rain. To 

 completely obviate the insulation defects in bad weather, and to protect 

 the line from thieves and lightning, it would be necessary to replace the 

 present pole line with a lead-covered cable buried in the ground. It is 

 hardly necessary to say that this was foreseen at the time when the line 

 was originally projected, as all installations of platinum thermometers up 

 to that date had been provided with lead-covered cables, especially in 

 cases where the distance involved was considerable. The original estimate 

 of 100?. for the apparatus was based on the assumption of a lead-covered 

 cable. But wheii the British Association in 1897 were unable to grant 

 more than 50/., it was decided to utilise the existing pole line rather than 

 abandon the project entirely. There is still some hope that the necessary 

 funds may be forthcoming for the replacement of the existing line by a 

 cable ; but until this necessary improvement is effected it is feared that 

 the scientific value of the work must be seriously impaired. 



Mectt'objsis and Eledru-chemistri/. — Report of the Committee, cumistincf 

 of Mr. W. N. Shaw (Chairman^ Mr. E. H. Griffiths, Eev. T. C. 

 FiTZPATRiCK, Mr. S. Skinner, and Mr. W. C. D. Whetham 

 (Secretary), appointed to report on the Present State of our Knoiv- 

 ledge iii Electrolysis and Electro-chemistry. 



The experiments on the conductivity of dilute aqueous solutions of salts 

 and acids at the freezing point have been completed by Mr. Whetham, 



