620 EEPOET— 1887. 



5. The otservalions of Mr. Abercromby on the motious of tbe upper clouds over 

 the equatorial zone, so far as they go, favour tbe notion of an E. to W. motion of 

 the upper air, and -would seem to show that this is unaflected by local influences 

 such as monsoons. 



6. The velocity of tbe current, though greater than that of any known constant 

 winds at tbe earth's surface, is by no means out of proportion to them if we may 

 assume the general law of increase of velocity with the height as deduced from 

 Dr. Yettin"s, and other cloud and wind observations to hold cfood to a height of 

 120,000 feet. 



For if we reduce the velocitv of 80 miles an hour at 120,000 feet down to 

 1,000 feet by the formula ' 



Y= VH 



we shall find it =-- 24-17 miles per hour ; and if we reduce this again to 100 feet by 

 the formula 



V V X 



which holds better than the former for heights below 1,000 feet, we shall get 11-2 

 miles per hour for the velocity near the surface, which would normally correspond 

 with a velocity of 80 miles an hour at an elevation of 1 20,000 feet above it. 



7. On a Co7nparison-magnetometer. Bij W. "W. Haldaxe Gee, B.Sc. 



This is a simple apparatus of great convenience for rapidly comparing the 

 moments of magnets by opposing them on opposite sides of a suspended magnet. 

 The magnets under comparison are placed on two wooden arms having millimetre 

 scales that are fixed at right angles to a box containing the suspended magnet. 

 For most experiments the formula M/M' = D-'/D'^, where M, M' are the moments 

 of the magnets, and D, D' the distances of their centres from the suspended magnet, 

 gives sufficient accuracy, providing that the magnets are not too long or too weak. 

 The method becomes one of difierences by taking double observations, and the 

 accuracy may be further improved by taking account of the lengths of the magnets 

 in the manner described in the paper. The apparatus is also adapted for electro- 

 magnetic and galvanometric measurements.^ 



8. On Exjjansion ic'dli Else of Temperature in Wires lender Elongating 

 Stress. By J. T. Bottomley, M.A., F.B.S.E., F.C.S. 



This paper gives a preliminary account of experiments undertaken for the pur- 

 pose of determining the longitudinal expansion with rise of temperature in wires 

 subjected to difi'erent elongating stresses. The investigation has been undertaken 

 partly in connection with the secular experiments on elasticity of -wires initiated 

 by a committee of the British Association in 1870. 



Two copper wires hung side by side in a tube of tin plate about 6 metres long 

 are alternately heated by steam and allowed to cool. One of these wires carries 

 one-tenth of its breaking-load ; the other, half of its breaking-load. 



After a preliminary process of hardening of the wires, found to be necessary 

 and described in the paper, comparisons were made as to the expansibility with 

 rise of temperature of the heavily loaded and lighth' loaded wires. 



The investigation is far from complete, but there seems no doubt that there is 

 a measurable difference between the two expansibilities, that of the heavily loaded 

 wire being the greater. 



The experimenting came to an end at the beginning of May, when the supply 

 of steam from the heating apparatus in the Glasgow University Laboratory ceased 

 to be available ; but the wires are left banging, carefully protected, and the investi- 

 gation will be resumed in October next. 



' Cf. Report of British Association for 1884, p. 639. 

 2 See Electrical Review, October 7, 1887, p. 370. 



