OF THE l7rn OF DECEMBER, 1896. 185 



of the eartli, wliilc> tliey also mark certaiu characteristics common 

 to both kinds of disturbance, which may lead (and probably have 

 actually led in the past) to a confusion of the two sources. Indeed, 

 with our present knowledge, we niay be permitted to suspect that 

 some, at least, of the older statements purporting- to relate to earth- 

 quakes may really refer to the effects of concussion of the air 

 produced by explosions at high altitudes in the air itself. 



But, however this may be, there can be no doubt that the shock 

 recorded in the south of England on 17th December is attributable 

 solely to a movement of the earth. 



Although some observers speak of movement of the air, and of 

 noise which might be associated with aerial shock, there can be 

 no doubt that the passage of an explosive meteorite through the 

 atmosphere at night would light up, and probably very brilliantly, 

 a great expanse of country. At half-past five in the morning on 

 17th December, the moon, though nearly fidl, was very low on 

 the horizon, and it is hardly possible that such a light as must 

 have been caused, had a bolide passed across the south of England 

 at that time, would have escaped the notice of the many persons 

 who are abroad during the night. 



It will be remembered, perhaps, that the bolide of the 2Cth 

 November was (so far as I could ascertain) actually seen by two 

 persons only, one at Hertford and the other at Solihull near 

 Birmingham ; but in that case the time was 8.20 a.m., and therefore 

 in broad daylight, and the weather was dull and foggy. 



An explosive bolide may, however, be distinctly seen in broad 

 daylight, and even in bright sunliglit when very near the surface 

 of the earth, though this is very uncommon. In Switzerland on 

 the 20th June, 1890, fi'agments of a luminous falling mass, which 

 had probably broken up very high in the atmosphere, were seen 

 in the afternoon in bright sunlight at three ditferent points many 

 miles apart by different observers, of whom I had the good fortune 

 to be one.'''' 



Apart from these considerations, it will be seen, on looking 

 through the various statements I have collected from Hertfordshire, 

 that the shock felt on 17th December, 1896, is generally described 

 as of a different character from that of 1887. Even a slight com- 

 parison of the statements printed in Vol. V of our ' Transactions,' 

 p. 35 et seq., with those incorporated in this paper, will establish 

 this distinction in the mind of the reader. 



I propose to deal with my materials very much as I did with 

 those I obtained in 1887, that is to say, to let observers speak for 

 themselves and in their own language. If this language is not 

 always scientific it is at all events natural, a characteristic of the 

 first importance in such matters as we have under examination. 

 It will be convenient to add a short general summary. 



Before proceeding to set out the statement of observers, I should 



* See "Note sur le bolide du 20 Juin. 1890," par H. G. Fordhara (' Bull. 

 Soc. Yaud. Sc. Nat.,' S"" serie, vol. xxvii, p. '2'20) ; and " A Meteorite observed 

 in Switzerland" ('Trans. Herts Nat. Hist. Soc.,' Vol. YI, p. 193). 



VOL. IX. — PART V. 13 



