34 



HARDWiCKE'S SCIEN CE-GOSS IP. 



find that as the sands dry they form systems of 

 cracks exactly similar in appearance to a river- 

 system, having maia valleys, with branches and 

 minor ramifications ; also, if a shower of rain falls, 

 it is in these cracks that the water will drain off. 



By the following simple experiment any one can 

 form systems of river-valleys, lake rock-basins, 

 volcanoes, faults, and the like ; and as it is sa easily 

 tried, the readers of Science-Gossip may judge 

 for themselves whether the statements of the 

 subacrialists are stable or unstable : — Get some 

 lime-mortar and a good-sized table or board. After 

 the mortal" is well mixed, incorporate in it some 

 pieces and fragments of unslaked lime (pieces only 

 partially burnt are best for the experiment) ; then 

 spread the mixture evenly with a trowel or flat 

 board on tlie table : as the pieces of lime begin to 

 slake, they will swell and form volcanoes (from 

 which will pop up a minute sliower of lime flour), 

 gradual upheavals, and systems of faults. If the 

 mortar is well mixed prior to adding the unslaked 

 lime, and the latter is only partly burned, cracks will 

 form in the plaster as it dries, before the lime 

 begins to slake, and the subsequent upthrows due 

 to the lime swelling will, in connection with them, 

 form the systems of faults. If, however, the lime 

 begins to slake before the plaster is dry and 

 cracked, a few long shallow cuts with a knife will 

 act similarly to the cracks. After the lime has all 

 slaked and the plaster is dry, the board or table 

 may be slightly elevated at one end, and then 

 subjected to a shower of water out of a very fine 

 garden syringe, or it may be put cut under a soft 

 rain. After these valleys, due to cracks, are sub- 

 jected to "rain and rivers," regular river-sj^stems 

 will form, valleys with sloping sides will gradually 

 be developed, while at the junction of two or more 

 cracks there will be minute lakes in typical rock- 

 basins. Moreover, in some valleys there will be 

 long narrow lakes, similar to the loughs so common 

 in mountain glens. Various other phenomena may 

 be studied in this simple experiment, but at present 

 I only wish to draw attention to the connection 

 between systems of cracks and rivcr-vallevs. The 

 thicker the coat of plaster the more marked the 

 results ; and the experiment may be varied by 

 spreading the plaster in layers, and not in one thick 



coat. G. II. KiNAHAN. 



NEW BOOKS. 



nnilERE are few sciences which liave made more 

 J- rapid strides than those of geology, electricity, 

 and magnetism. The latter subjects lie some\vht,t 

 out of our usual lino, but we are nevertheless glad 

 to have the opportunity of recommending to such 

 of our readers as r,rc interested in these important 

 sciences, or who wish to know something about 



them ; a book* which has been before the world for 

 more than twenty years, has done great good during 

 that time, and has now reappeared in an enlarged 

 and revised form, under the able editorship of 

 Professor Noad. This little work impresses us as 

 being exactly the kind of book to put into the 

 hands of a youth interested in magnetic and elec- 

 trical science. It includes the history of discovery 

 in these departments, more particularly a lucid 

 summary of the researches of Faraday and others. 

 The clear and attractive style in which it is written 

 and edited shows that both author and editor are 

 fully en rapport with their readers^ 



The next workf is more in our line. We have 

 frecpiently been asked to recommend a good work 

 on elementary geology, and have found a difiiculty 

 in doing so. Scientific writers are apt to take too 

 much for granted on th-3 part of tlieir readers, and 

 we think that even Mr. Tate is not altogether free 

 from this common error. But it is, in our opinion, 

 the best of its class, whilst its price will bring it 

 within the reach of the poorest student's slender 

 pocket. This book is partly based on the well- 

 known rudimentary treatise on geology by Major- 

 General Portlock, originally published in Weale's 

 series. The additions, however, and especially the 

 number of illustrations, have made quite a new 

 book of it. We like the author's arrangement, and 

 especially the clear and unbiassed manner with 

 which he has placed before his readers the views of 

 diiferent geologists on moot questions. If any- 

 thing, the work is too full, and the reader is apt to 

 be bewildered by the number of subjects brought 

 before him, and the haste with which the limited 

 space obliges the author to pass over them. 



The next worksj are all pretty much of the same 

 cliaracter— that is, they have a kind of scientific 

 basis, which serves for the books pretty much as a 

 text does to a sermon. The latter is frequently 

 taken by the preacher, and there is an end of it. The 

 two first books are marked chiefly by rhapsody. They 

 contain many fine passages, and some suggestive 

 ones. The reader, however, cannot get away from 

 the feeling that everything is being strained to the 

 utmost. The views of Michelet, who is a disciple 

 of the Eourier school, are now pretty well known 

 in England. Regarding the earth as herself an 

 animate being, whose natural phenomena are but 

 the expressions of her varied life, it is not dilEcuIt 



• "Rudimentary Magnetism." By Sir W. Snow Harris, 

 F.R.S., ^c. Revised and enlarg'ed by Dr. IT. M. Noad, F.R.S. 

 Lockwood & Co., Londcn. 



t "Historical Geology." By Ralpli Tate, r.G.S., &c. 

 London: Locltwood & Co. I8"l. 



% " Tiie Mountain," from the French of Michelet. By the 

 Translator of " The Bird . " 



"Nature; or, the Poetry of Earth and Sea." From the 

 French of Madame Michelet. 



" Beautiful Birds in far-off Lands ; their Haunts and 

 Homes." By Mary and Elizabeth Kirby. London : T. Nel- 

 son & Sons. 



