H. E. Sippidey — Somersetshire Coal-measures. 345 



wliich will gradually give way before the tendency which the 

 mountain will always have, namely, to assume that position in which 

 the materials are best arranged to afford to each other a mutual 

 support, and this position appears to be that of the logarithmic curve 

 which has been described. 



We have not yet considered that these mountains have to support 

 anything but their own weight, but as Rankine has shown that the 

 logarithmic form is the best for revetement walls, or walls of re- 

 servoirs, etc., without going into calculations, it will be evident that 

 these regular volcanos are also strong enough to support the pressure 

 of a column of lava of their own height. 



In conclusion, I may remark that just as it is possible that the 

 fiery mountains and earthquakes of Japan impressed its inhabitants 

 with wonder and superstition, so the beautiful forms of the volcanos 

 may have been the first suggestions for the curvatures we see upon 

 the roofs of houses, and for the massive walls which bound the moats 

 and support the embankments of all the castle towns. How far this 

 may be true, I do not know, but certainly the form which has of late 

 years been shown the most stable for such structures, is one which 

 in Japan has reached its millennium. 



EXPLANATION OF PLATE IX. 



Profiles of Volcanos traced from Photographs. 

 No. I. Upper portion of Fusiyama, taken from near Marayama, S."W. side. 

 No. II. Fusiyama, from near Hitoana, "West side. 

 No. Ill, Fusiyama, from Suyama and Gotemba, S.E. side. 

 No. IV. Kumagatake, as seen from near Hakodate. 

 No. V. Monte Somma and Vesuvius. 



The shaded portions sho-w irregularities in the curvature of the mountains. 

 These, it will be observed, are very small 



The broken line on the right of No. II. is a logarithmic curve drawn 



for purposes of comparison. 

 It suggests that No. II. was once logarithmic, but the upper portions of the 

 mountain have been washed to the bottom to render the mountain less steep 

 both above and below. 

 It also might indicate that the phenomena, spoken of by Mr. Mallet, had taken 

 place, namely, that the weight of the central portion of the mountain had 

 caused an elevation round the base. 



II. — Somersetshire Coal-measures. 

 By H. E. HippisLEY, M.A., C.E. 



IT will probably be conceded, by those who have studied the 

 Somersetshire portion of the British Coal-field, that the cor- 

 relation of the various parts of it is not, at the present time, so 

 perfect that any attempts to improve it are entirely uncalled for. 

 The following conjectures ' as to whether some of the facts relied on 

 as proving the commonly-accepted theory of the structure of the 

 Somersetshire Coal-measures, and their general coiTelation with 

 those in Gloucestershire, may not possibly admit of an interpretation 

 differing from that usually assigned to them ; are put forward in 

 the hopes of indicating a line of research which may eventually, 

 when modified by the results of further investigations, lead to a 

 1 Being a brief summary of an unpublished paper on the subject. 



