130 Prof. 0. I. Burton and Mr. W. Marshall. [June 18, 



Tables show that the amount of disturbance, especially of horizontal 

 magnetic force, is nearly the same at widely distant stations. 



An attempt has also been made to apply the Gaussian analysis to 

 sudden magnetic disturbances, and, with a view to their application 

 in future work, the values of the Gaussian functions have been ob- 

 tained for 20 different Observatories, and the numerical equations 

 formed for the elements of magnetic force in three directions 

 mutually at right angles, and also the equation for the magnetic 

 potential in terms of the Gaussian coefficients to the fourth order. 



The Tables give the numerical values to be multiplied by the 24 

 Gaussian coefficients to give the values of the forces X, Y, and Z in 

 the geographical meridian towards the north, perpendicular to the 

 meridian towards the west, and vertically downwards respectively. 

 The equations are also formed and the values obtained in terms of 

 the 24 Gaussian coefficients for X 2 , Y 2 , and Z 2 , X 2 being the horizontal 

 force in the magnetic meridian, Y a the horizontal force perpendicular 

 to the magnetic meridian, and Z 2 the vertical force. If then X 2 , Y^, 

 and Z 2 be the observed values of any simultaneous disturbances, they 

 may be at once substituted in the equations, the equations giving the 

 24 Gaussian coefficients may be solved, and the corresponding change 

 of magnetic potential may be determined. , 



VII. " On the Measurement of the Heat produced by Compress- 

 ing Liquids and Solids." By the late COSMO INNES BURTON, 

 B.Sc., F.C.S., Professor of Chemistry, Polytechnic, Shang- 

 hai, and WILLIAM MARSHALL, B.Sc., F.C.S. Communi- 

 cated by Professor THORPE, F.R.S. Received June 10, 

 Read June 18, 1891. 



In the year 1885 Messrs. Creelman and Crocket ('Edinburgh Roy. 

 Soc. Proc.,' vol. 13. p. 311), under Professor Tait's supervision, per- 

 formed a series of experiments on the beat produced by the compres- 

 sion of various substances. Their method was briefly as follows : 

 For the application of the pressure, the same apparatus which we 

 describe and figure later was used. A thermo-electric junction of 

 insulated nickel and iron wires was fixed between the leather washers 

 and a sufficient length of wire coiled away inside the gun to allow the 

 junction to be drawn out at the top and a specimen attached to it. 

 Among the substances examined were glass, cork, vulcanite, glue, 

 bees'-wax, and paraffin oil, the only pure chemical compounds being 

 chloroform and ether. The following are some of the results obtained. 

 Pressure, about 1 ton on the square inch. 



