502 TRANSACTIONS OF SECTION A, 



of the eartli, the ludiau area representing the centre of one region, while that of 

 South America -was typical of the opposite or reverse change. It was then shown 

 ' that the rainfall underwent changes which were closely related to this pressuve- 

 variation of short duration. 



The author then referred to an investigation he had recently communicated to 

 the Royal Society (vol. Ixxviii., p. 4.3), in which pressure -changes of longer 

 duration were examined. 



It was thought possible that similar barometric see-saws might occur with 

 regard to the changes of long duration as were found for those of short duration. 



The result of the inquirj^ indicated that, while there was a variation of about 

 eleven years' duration occurring in India, a nineteen-year variation was conspicuous 

 in the Australian and South Americaii areas. 



In the case of the last two mentioned areas the phases were neither coincident 

 nor reverse, but there seemed to be a lag of about six years. 



It was finally suggested that, as tlie Australian variation was closely allied to 

 the Indian change, and as the Indian pressure-change is closely similar to the 

 reverse of the sun-spot variation, the Australian nineteen-year cycle was possibly 

 of solar origin, and not necessarily due to lunar influence. 



7. lii'.'port on the Mayjiefic Observations at Falmotilh Observatory. 



See Reports, p. 90. 



8. PreJUninanj Jifpori on the Magnetic Snrvrr/ of South A/rira. 



Sec Reports, p. 131. 



Rppoi't 071 Metaorolofiical Observations on JJi'ti Averts. 

 iSee Reports, p. 91. 



Depahtment op Geneual Physics. 

 The following Papers were read : — 



1. A Glass of Loxo Resistivity. By Charles E. S. Phillips. 



A glass which conducts electricity comparatively well may be obtained by 

 fusing together sodium silicate and borax in the following proportions, viz., 



Sodium silicate .,,,,, .32 parts. 

 Calcined borax 8 parts. 



If to this mixture \-2'> parts of Powell's flint glass be added, greater 

 stability results, and the surface is improved without any serious loss ot 

 conductivity. 



A glass suitable for the cases or windowsof electrostatic instrumerits may thus 

 be produced, capable of being east into plates, but on account of its low fusion- 

 point not otherwise very workable. It may, of course, be readily drawn into 

 rods or fibres, and takes a fine polish. 



The density of the glass is 2490, and it is somewhat harder than the 

 ordinary soda glass of commerce. 



With regard to other physical properties, it shows no fluorescence under 

 cathode radiation, is very transparent to .c-rays and opaque to ultra-violet light. 

 Its electrical conductivity is about 500 times that of the most conducting glass 

 so far made. The specific resistance of an average sample is of the order 

 10^ ohms at 20° C, which, although high in itself, is exceedingly low for 

 glass. When powdered and fused on to clean copper it adheres well without 

 cracking. The change of repistivity with heat (which is \ery marked) is being 

 examined. 



