SCIENTIFIC SUMMARY. 
333 
From some experiments on the Influence of Temperature on the passage 
of air through capillary tubes, Dr. Francis Guthrie concludes : — 
(1.) That the time varies approximately as the square of the absolute 
temperature. 
(2.) That the variation of the time deviates from the law of squares 
by a term approximately proportional to the temperature. 
(3.) That the formula connecting the time and the temperature is 
nearly 
t = d T (T -h/3) 
where T is absolute temperature reckoned from — 273° 0., and /3 seems 
to depend on p x — p< z or the difference of pressures, the exact relation 
not being obvious. 
Thermo-Electric Currents in Strained Wires have been investigated by 
Mr. G. W. von Tunzelmann. The object in view was to determine the 
conditions under which thermo-electric currents are produced in a circuit 
composed of a single metal, when one portion of the metallic conductor is 
subjected to a strain, and the strained and unstrained portions are main- 
tained at different temperatures. 
“ Two tin cans were obtained, open at the top, and pierced at the bottom 
by necks, into which India-rubber corks were inserted ; through slits in these 
the wires were passed. The wire was fastened by a clamp in the lower 
can, and grasped in the upper by a pair of wire-drawing dogs attached to 
the shorter arm of a lever, to the longer arm of which was attached another 
tin can, open at the top, and having at the bottom a neck fitted with an 
India-rubber tube, which 'could be closed by merely bending it up and 
hitching it in a hook attached to the can for that purpose. The strain on 
the wire was then produced as gradually as possible by pouring in measured 
quantities of shot. It could be removed as gradually by letting the shot run 
out by the India-rubber tube. 
“The two cans through which the wire passed were kept, one at 100° 0, 
the lower, at the surrounding temperature by a stream of water. 
“ The ends of the wire were connected with a Thomson’s Galvanometer. 
“ As the strain was increased the current was increased, but only up to a 
certain limit. When it was carried beyond this point there was a gradual 
decrease in the current. If the strain was very carefully increased the 
direction of the current was reversed shortly before the breaking strain was 
reached.” 
Ten such experiments are recorded, from one of which a diagrammatic 
curve is obtained. 
On the pitch of a tuning-fork in an incomp'essible fluid, by Felix Auerbach. 
When a tuning-fork is plunged in water, a note, not agreeing with that in 
air, is given out, the dissipation of kinetic energy taking place in incom- 
pressible fluid differently from that occurring in air. The tone becomes 
deeper in the ratio \f 1*4 : 1, i.e., as D18 : 1, or about as 7 : 6, more, there- 
fore, than a' tone, and less than a minor third. 
The fall in pitch was determined by means of beats between a fork im- 
mersed in water and another, of a tone lower, in air. It appears that the 
resistance of liquids depending on density and viscosity does not come 
sensibly into consideration as regards wave lengths, though it does as regards 
