124 



HA RD WI CKE 'S S CIE NCE- G SSIF. 



From more recent observations I concluded that 

 the seismic vertical was at or near Dr. Green's house, 

 close to the strood or causeway which connects the 

 mainland of Essex with Mersea Island. The house 

 was built in i860, and is therefore new. I may here 

 observe that (as I hinted before) the modern, cheaply- 

 built cottages were not so much affected as the 

 more ancient ones. The chimneys, walls, &c., of 

 the latter were invariably destroyed, damaged, or 

 cracked — those of the former seldom so. I was 

 much surprised at this. The first thought naturally 

 was that these "jerry built " houses would be shaken 

 down like a pack of cards. Is it that their very 

 looseness of structure is in their favour, as compared 

 with the stronger built cottages of two and three 

 hundred years ago ? I have somewhere seen that in 

 earthquake-visited centres, the houses most secured 

 from destruction are the loosely-built, low edifices. 

 One can speak plainly on this matter, as no premium 

 is required to encourage the development of "jerry 

 building." Dr. Green's house is literally split and 

 cracked in all directions, and the splits and cracks 

 are the most vertical of any to be seen. The entire 

 building was twisted on its foundations. At the 

 south'west corner this is visible to the amount of 

 about one inch and a half. Dr. Green informed me 

 he was lifted up, as if from behind, and shot violently 

 forward. A friend of mine remarks (and I noticed 

 the same fact in my note book, but omitted enclosing 

 it in my first communication) that the railway cutting 

 at Wivenhoe appears to have broken the continuity of 

 the undulations, for the houses contiguous to it are 

 comparatively uninjured. A noteworthy fact in 

 connection with the recent earthquake, to which I 

 can personally testify, and which appears to be the 

 general experience of all the most trustworthy 

 observers I have come across, is that the sounds or 

 noises preceded the oscillations for an appreciable 

 period of time. Mallet's experiments showed that 

 the shock of an explosion travels through wet sand 

 at the rate of 951 feet per second. In Ipswich we are 

 situated chiefly on drift sands and London clay, and 

 allowing that the earthquake shocks travelled through 

 these strata at a more rapid rate, it is not likely to 

 have been much more rapid. As sound travels at 

 the rate of 11 18 feet per second, it is very probable 

 that the noise accompanying the earth-movements 

 preceded the oscillations. 



Mr. Wilkins, the well-known yacht-builder at 

 Wivenhoe, tells me he was standing at the time the 

 earthquake occurred in the yard, and his first im- 

 pression was that a new yacht he was looking at was 

 heeling over, and he called out so to his workmen in 

 the shop close by. Then followed the crash of the 

 tall chimney and the rending of the walls. The work- 

 shop has an upper floor with windows on each side, 

 and, as he stood in the yard, Mr. Wilkins says the 

 oscillatory waves were such that he was enabled to 

 look right through these windows, so as to see the 



falling chimneys of the buildings on the other side. 

 He calculates there must have been a rise and fall of 

 the ground of two feet nine inches to have enabled 

 him to do this. 



In view of Mr. Topley's suggestion that the earth- 

 quake probably has some connection with the ridge 

 of palaeozoic rocks [which underlies the eastern 

 counties, it would be interesting to know if the 

 shocks were felt in the Boulonnais and the Ardennes, 

 as they were in the Mendip Hills — the other end of 

 the chain which is let down beneath London, and 

 covered up with chalk and Tertiary strata. , 



J. E. Taylor. 



FREE-SWIMMING ROTIFERS. 



IN the course of my study of the rotifera, I often 

 come across forms, especially in the more 

 minute free-sv/imming ones, which I am unable 

 satisfactorily to make out. The Micro. Diet, does 

 little beyond giving generic differences, while " Prit- 

 chard," an invaluable book, is yet far from being all 

 that a student of these animals could wish. A short 



Fig. 67. — Side view. 



Fig. 68. — Dorsal view. 



time ago an announcement was made, I believe at a 

 meeting of the Manchester Microscopical Society, 

 that some authority was engaged in preparing a 

 manual on this subject. If this could receive an 

 authoritative confirmation, it would gladden the 

 hearts of many students of these animals. From 

 Saville Kent's preface to "A Manual of the In- 

 fusoria," we gather that this work was originally 

 intended to be based upon the same lines as " Prit- 

 chard's Infusoria," but there was an accumulation of 

 such a quantity of material, as to render a more 

 limited scope desirable. If from the materials which 

 he had undoubtedly gathered together, he would 

 supplement his magnificent work by one on the 

 rotifera, especially if it could be issued in shilling 

 monthly parts, he would confer a boon on hundreds 

 if not thousands, of enthusiastic workers on this 

 subject. 



I send sketches from my " Note Book," of a rotifer 



