78 Notes and Memoranda. 



NOTES AND MEMORANDA. 



A Water Barometer in a Thunderstorm. — The following description of 

 the action of a water barometer during a terrific thunderstorm at Birmingham, 

 on July Sth, is by Mr. Alfred Bird, of that town. The fall of rain was unpre- 

 cedented, and a storm of thunder and lightning raged from Hi. to 3h. p.m., 

 which sacrificed one life in Birmingham, besides doing much damage to property 

 at Balsall Heath, "Wednesfield Heath, Wolverhampton, and other places : — *' Mr. 

 A. Bird, of Worcester Street, has a water barometer fixed upon his premises, and 

 the action of the storm upon it was of a most remarkable description. In a 

 barometi r of this kind the water rises 13g inches for every inch on the ordinary 

 mercurial barometer, and the action is, therefore, most distinct. When the storm 

 commenced the column of water stood at 389 inches, which would be equal to 

 29J on the ordinary barometer. As the storm progressed, the oscillations in the 

 water were from half an inch to an inch, and at nine o'clock in the evening, the 

 barometer stood at 391^, and was then steadily rising. At every flash of lightning 

 there was an instantaneous fall of the column of water from a quarter to half an 

 inch, and then a gradual rise as the rain came on. The movements were remark- 

 ably interesting. When the electric disturbance had ceased, the column of water 

 gradually ro*e, indicating that the density of the atmosphere was steadily in- 

 creasing. Thi3 water barometer is, we believe, the only one in existence in the 

 county at present." The instantaneous fall of the column of water from a quarter 

 to half an. inch at every flash of lightning is remarkable, corresponding apparently 

 to sudden jumps of an electrometer, observed in thunderstorms. The column of 

 fluid in a barometer is balanced as delicately as the gold leaves in a gold leaf 

 electrometer. Being attracted by the free electricity in the atmosphere, it is not 

 impossible that it might oscillate in a similar manner. At every flash of lightning 

 a certain quantity of free electricity suddenly disappears, and the column of 

 water is instantaneously let fall. If this be a true explanation of the phenomenon, 

 the water barometer, in wlrch the movements are greatly magnified, is at one and 

 the same time a barometer and an electrometer. The distinctive character of the 

 storm illustrates the great increase of electric tension with the magnitude of the 

 fall of rain. The rain-fall in this instance amounted to 153 inch in two hours, 

 a quantity only common between the tropics, and fortunately of very rare occur- 

 rence in our latitudes. A particular form of aneroid by Mr. Browning, described 

 in Intellectual Observer, vol. vi., p. 38, would, as pointed out by us, probably 

 be the most convenient instrument for -testing these questions. We should much 

 like to see one of these instruments suitably placed. 



Comparative Luminosity of Venus and the Moon. — M. Chacornac has 

 been able to carry out in the neighbourhood of Lyons a plan of measuring the 

 relative intensity of the light reflected by equal surfaces of Venus and the moon. 

 He employs an apparatus for doubls refraction and polarization, to which we 

 have before alluded, and his experiments were made on the 201 h June, at three 

 a.m., when Venus and the moon were in conjunction. With a magnification of 

 70, the extraordinary image of Venus was visible in all its outlines, when only 

 one two-thousandth of its light was permitted to reach the eye. Under these 

 circumstan' es the dimensions of the planet were noticeably diminished, as M. 

 Chacornac had previously found with reference to Jupiter. A brilh'ant portion of 

 the moon, between the craters Rocca and Eichstadi", S.E. of G-rimaldi, was selected 

 for comparison, and it was found that the greatest reflecting power of the moon 

 was only a tenth of that possessed by Venus. M. Chacornac could not detect any 

 trace of polarized light in Venus, though it is very noticeable in the moon, and 

 he considers that the light we receive from Venus is refli-cted from a continuous 

 surface of clouds, and that the spots seen on her disc was not permanent, as Do 

 Vico supposed. 



Sun Spots and Jfptter Spots.— M. Chacornac has kindly sent us engravings 

 of equatorial spots seen on Jupiter at half-past eight and half- past nine p.m., October 

 13th, 1856, in order to show their resemblance to sun spots (also engraved) seen at 



