382 



Messrs. R. H. Scott and R. H. Curtis. [May 20, 



been obtained exhibiting the expansion of the liquid, the pressure of 

 the vapour, and the compressibility of the substance in the gaseous 

 and liquid conditions; and from these results, the densities of the 

 saturated vapour and the heats of vaporisation have been deduced. 

 The temperature range of these observations is from —18° to 223° C. 



It is the authors' intention to consider in full the relations of the 

 properties of alcohol and ether ; in the meantime it may be stated 

 that the saturated vapour of ether, like that of alcohol, possesses an 

 abnormal density, increasing with rise of temperature and corre- 

 sponding rise of pressure ; that at 0° the vapour-density is still 

 abnormal, but appears to be approaching a normal state ; and that the 

 apparent critical temperature of ether is 194 , 0°C. ; the critical pressure 

 very nearly 27,060 mm. = 35*61 atmospheres ; and the volume of 

 1 gram of the substance at 184° between 3*60 and 4 c.c. 



III. " On the Working of the Harmonic Analyser at the Meteoro- 

 logical Office." By Robert H. Scott, F.R.S., and Richard 

 H. Curtis, F.R. Met. Soc. Received May 6, 1886. 



On the 9th of May, 1878, Sir W. Thomson exhibited to the Society 

 a model of an integrating machine, which consisted of a series of five 

 •of the disk, globe, and cylinder integrators, which had been devised 

 two years earlier by his brother Prof. James Thomson, and a descrip- 

 tion of which will be found in the " Proceedings of the Royal Society," 

 vol. xxiv, p. 262. Sir W. Thomson's paper describing this model 

 will be found in vol. xxvii of the " Proceedings," p. 371 ; and refer- 

 ence should be made to both these papers for an explanation of the 

 principle of the machine. In the communication last named it is 

 stated that the machine was about to be " handed over to the 

 Meteorological Office, to be brought immediately into practical work." 



The model was received at the Office in the course of the month, 

 and was at once set in action ; the results of the preliminary trials, 

 when obtained, being referred to a Committee consisting of the late 

 Prof. H. J. S. Smith and Prof. Stokes, who, on the 5th of July fol- 

 lowing, submitted to the Meteorological Council a favourable report 

 on the performance of the model. 



The Council at once resolved to have a machine constructed, which 

 should be specially adapted to the requirements of the work for which 

 it was intended, viz., the analysis of photographic thermograms and 

 barograms. 



In preparing a working design for actual execution, it was found 

 necessary to make several modifications in the details of the mechani- 

 cal arrangements of Sir W. Thomson's original model, and these were 



