60 Mr. G. J. Symons. On Barometric Oscillations [May 8, 



phenomenon ; and no one in England seems to have been aware of it 

 until the photographic barometer was started at the Radcliffe Obser- 

 vatory, Oxford. Manuel Johnson, when describing the new instru- 

 ments at the British Association meeting at Glasgow, in 1855, 

 said : 



" Among the most remarkable results is a sudden rise of the 

 barometer, amounting to 0'035 in., and an increase of temperature of 

 1, coincident with the occurrence of a thunder clap which struck 

 one of the churches in Oxford, July 14th, 1855. A similar phe- 

 nomenon took place during a thunderstorm on August 23rd, when 

 the rise of the barometer was still greater, amounting to 0'049 in., 

 though the thunder clap coincident with this rise was distant." 



Mr. Johnson returned to the subject in the volume of ' Radcliffe 

 Observations ' for 1857, and gave reproductions of fourteen barograms, 

 but the scale is so compressed (only \ in. per hour, and 1^ in. per 

 inch of mercury) that not much is to be learned from them beyond 

 the fact of falls occurring of 0'037 in., O040 in., and 0'046 in., and a 

 rise of 0'070 in. ; the notes on the storms are also too vague to be 

 useful. It may, however, be well to quote the conclusion at which 

 Mr. Johnson arrived, viz. : 



" A comparison of these notes with the accompanying illustrations 

 cannot, in my opinion, fail to lead to the inference that the disturb- 

 ances exhibited both on the barometric and the thermometric curves 

 (especially the former) are caused by the presence of electricity in 

 the atmosphere, of which we had on these occasions sensible proof. 

 But they are the more interesting, from the circumstance that 

 similar disturbances occur not unfrequently when there has been no 

 overt manifestation of that agency ; especially during the winter 

 months, when, according to the concurrent testimony of all observers, 

 atmospheric electricity is most abundant." 



The next observation of importance is one quoted by Le Verrier, 

 as reported to him by the observer, M. Goullon, Cure of Saint-Ruffine 

 (Moselle). He had two barometers, a mercurial and an aneroid. On 

 the morning of February 5th, 1866, the weather being stormy with 

 heavy rain, wind S.W., moderate, but not squally, he had just set and 

 read his barometers, when there was a solitary loud clap of thunder, 

 and instantly both his barometers rose 2 mm. (0'08 in.). 



The Hon. Ralph Abercromby began studying these oscillations in 

 1868, arid in 1875 summed up the results in the following sentences, 

 one descriptive, the other explanatory : 



" There are two classes of storm in this country : in the one the 

 barometer rises, in the other it falls. In the case in which it rises, 

 the sequence of weather is somewhat as follows : After the sky has 

 become overcast, the wind hushed to an ominous silence, and the clouds 

 seem to have lost their motion, the barometer begins to rise suddenly. 



