June 1, 1899.] 



KNOWLEDGE 



121 



Mi 



IILUSTRATED MACAZINEIi; 



.ITERATl 



Founded by RICHARD A. PROCTOR. 

 LONDON: JUNE 1, 1S99. 



CONTENTS. 



Bv Charles 



The Hereford Earthquake of 1896 



Davison, sc.d., f.q.s. (Biar/ram) ... 

 The Discoloration of Cut Apples. By G. Clabke 



NUTTALL, E.SC. 



On the Treatment and Utilization of Anthropological 



Data. — III. Racial Proportions. By Aethfk 



Xhomson, M.A., 5r. B. (Diagram) ... 

 Secrets of the Earth s Crust.— 111. The Makers of Flint. 



By GrRENVlLLB X. J. CoLE, M.R.I.A., F.o.s. {Illustrated) 

 A New Satellite of Saturn. By Ebwaed C. Piceeei.vo 

 Nebulous Region Round the Cluster N. G. C. No. 2239 



Monocerotis. By Isaac Robebts, d.sc, f.e.s. {Plate) 



Letter : Frances I. Batteesby 



Science Notes .„ 



British Ornithological Notes. 



WiTHEEBY, F.Z.g., M.B.O.IJ. .. 



Notices of Books , 



Books Receited 



Wireless Telegraphy 



The Karkinokosm, or World of Crustacea. — IX. 



Dignite du Chezsoi. By the Rev. Thomas R 



Stebbino, ji.a., f.e.s. , F.jj.s., F.z.s. {Illustrated) 

 Microscopy. By John H. Cooke, r.L.s., e.g.s. {Illustrated) 

 Notes on Comets and Meteors. By W. F. DENNiNa, 



F.E.A.S 



The Face of the Sky for June. Bv A. Fowlbb, p.e.a.s. 



{Illu.itrated) ... ', 



Chess Column. By C. D. Lococe, b.a. ... .'.'. 



Conducted by Haeey F. 



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THE HEREFORD EARTHQUAKE OF 1896.* 



By Charles DA\asoN, sc.d., p.g.s. 



THOUGH slight earthquakes are not at all uncommon 

 in this country it is fortunately but seldom that we 

 are visited by a shock so strong and so destructive 

 to property as that which occurred near Hereford 

 on the morning of December 17th, 1890. The Essex 

 earthquake of 18H4 was productive of greater damage 

 within a limited district, but the area disturbed by it is 

 estimated at not more than fifty thousand square miles. 



The accompanying map will show at a glance how much 

 greater was the area aifected by the Hereford earthquake. 

 It includes the whole of England and Wales, with perhaps 

 the exception of the three northern counties of Northum- 

 berland, Durham and Cumberland, and extending across 

 the channel, entrenches upon the south-eastern counties 

 of Ireland. The outermost continuous line (called the 

 " isoseismai 4") bounds the region within which the 

 shock was strong enough to make doors, windows, etc., 

 rattle, but if the earthquake had not occurred at so early 

 an hour (5.32 a.m.) there can be little doubt that it would 

 have been perceived far beyond these limits. However, it 

 was observed at the point of Ayre lighthouse (in the north 



* Abstract nf the writer's work on "The Hereford Earthquake of 

 December 17th, 1896," published by Cornish Brothers, Birmingham. 



of the I.=le of Man), at Middlesborough, and at Flamborough 

 Head lighthouse. Eecords have also come from morp 

 distant places, but, as these are somewhat isolated, it is 

 not quite certain that they refer to the earthquake. The 

 furthest from the bounding line just mentioned are Ack- 

 lington, in Northumberland (fifty-nine miles distant), and 

 Killeshandra, in County Cavan (sixty-five miles), and it is 

 worthy of notice that the times at which the disturbances 

 were observed at these places do not differ greatly from 

 what they should have been, taking into account the velocity 

 with which the earth-wave radiated from the origin. 



It will be seen that the outermost line is very nearly 

 circular in form, its dimensions being three hundred and 

 fifty-six miles from north-west to south-east, and three 

 hundred and fifty-seven miles from north-east to south-west. 

 The area included within it is ninety-eight thousand 

 square miles. If, however, the disturbed area were bounded 

 by a concentric circle passing through Middlesborough, it 

 would then contain one hundred and fifteen thousand 

 square miles ; and if by one through Killeshandra, as 

 much as one hundred and eighty-five thousand square 

 miles. Thus, the disturbed area can hardly have been 

 less than one hundred thousand square miles — that is, it 

 was at least twice as great as that afi'ected by the Essex 

 earthquake. 



The continuous oval curves drawn upon the map 

 represent iso.Kiviud lines or lines of equal intensity of the 

 shock ; and are determined by reference to the Rossi- 

 Forel scale of seismic intensity, an arbitrary scale in which 

 the degree 1 corresponds to shocks so slight that they 

 could only be felt by the most experienced observers, and 

 the degree 10 to disastrous earthquakes by which whole 

 towns and villages are overthrown. With the two highest 

 degrees of this scale we have fortunately nothing to do in 

 this country. The greatest intensity ever experienced by 

 us, at any rate during the present century, is that 

 numbered 8 in the scale, which refers to a shock capable 

 of throwing down chimneys or cracking the walls of 

 buildings. In the Hereford earthquake, damage of this 

 kind occurred at no less than seventy-three places, fifty- 

 five of which were in the county of Herefordshire. 

 Marking these places on a map, and also those at which, so 

 far as known, there was not the least damage done to 

 buildings, and then drawing a line so as to include all the 

 former and exclude the latter as far as possible, we obtain 

 an isoseismai line corresponding to the degree S of the 

 scale, a line which we may for brevity call the isoseismai 8. 

 Outside this line, no buildings were injured in any way, 

 except in a few isolated cases. Thus, at Knightwiek, two 

 miles from the curve, stones fell from the top of a tall 

 church spire, and, at three other more distant places, 

 solitary chimneys were more or less damaged. The 

 greatest destruction occurred in the city of Hereford 

 and in some of the neighbouring villages. The cathedral 

 escaped without very serious harm, but, in addition to 

 some other slight injury, the three pinnacles at the west 

 end were cracked near the top, and in each the upper 

 detached portion was slightly displaced. The spire of 

 St. Martin's Church was cracked right through about 

 twelve feet from the top, and at Barr's Court railway 

 station all the seven chimney-stacks were shattered. Prom 

 inquiries made among builders in Hereford, Mr. H. Cecil 

 Moore ascertained that certainly not less than two hundred 

 and eighteen chimneys had to be repaired. At Dinedor, 

 three miles south-east of Hereford, all the vicarage chimneys, 

 eight in number, were knocked down and had to be rebuilt. 

 And again at Fownhope, three miles further to the south- 

 east, many chimneys were thrown down, and in falling 

 caused much damage to the roofs of houses. These three 



