October 2, 1890] 



NATURE 



543 



tfor examination. The book will be sure to be well used, 

 .and we recommend it, and with the authors we hope 

 " that it may stimulate others to make the teaching of 

 physical geography a pleasant exercise for themselves 

 and a valuable mental training for those whom they 

 teach.' W. 



The Evolution of Photography. (Illustrated.) By John 

 Werge. (London : Piper and Carter ; John Werge, 

 1890.) 



In this work we have a most interesting account, arranged 

 in chronological order, of the origin, progress, and de- 

 velopment of the science and art of photography. The 

 author has divided this time into four periods. The first 

 deals broadly with facts bearing on the accidental dis- 

 covery of photography, and on the early researches and 

 ultimate success of the pioneers. The second embraces 

 a fuller description of their successes and results, while 

 the third is devoted to the consideration of patents and 

 impediments, and the fourth to the final development of 

 both photographic literature and art. 



Although the author has not entered minutely into 

 elaborate details of each process, yet he has given 

 ■enough to form an interesting summary. Excellent 

 illustrations of some of the chief photographic investi- 

 gators, taken from paintings, daguerreotypes, &c., and 

 reproduced by the callotype process, add greatly to the 

 value of the book. 



Following this there is a chronological record of inven- 

 tions, discoveries, publications, and appliances connected 

 with the development of photography, and the author 

 concludes with the personal reminiscences, extending over 

 a period of forty years. 



This book will be an acceptable addition to our photo- 

 graphic literature, and will be found interesting not only 

 by the practical photographer, but by many amateurs. 



W. 



Geometrical Drawing for Art Students. By I. H. Morris. 



(London: Longmans, Green, and Co., 1890.) 

 Art students will be glad to find in this work a com- 

 pendium of those parts of geometry which cover the 

 necessary range for their course. Plane geometry and its 

 applications, the use of scales, and the plans and eleva- 

 tions of solids, are treated concisely, and the method 

 adopted throughout of placing the text on the left-hand 

 pages, leaving the right-hand pages solely for figures, will 

 be found most convenient. The figures are all neat 

 and well drawn, those illustrating the problems on solid 

 geometry being especially so. 



The chapter on the construction and use of plain and 

 diagonal scales and scales of chords, subjects which are 

 generally stumbling-blocks to a great many students, is 

 made very clear, and in chapter xv. good ideas are im- 

 parted in the applications of geometry to the construction 

 of patterns and simple tracing. 



Nearly six hundred figures are inserted in the book, 

 together with a complete and exhaustive collection of 

 exercises. Students interested in this subject other than 

 those for whom the work is intended will find the 

 arrangement adopted more convenient than in many 

 other books on the subject. W. 



An Elementary Text-book of Dynamics and Hydrostatics. 

 By R. H. Pinkerton, B.A. Oxon. Second Edition. 

 (London: Blackie and Son, Limited, 1890.) 



We are glad to see the appearance of a second edition 

 j of this serviceable little text-book, the first edition 

 j of which we reviewed some time ago. No material 

 I alteration has been made in any part of the work. The 

 i appendix has been extended by the introduction of the 



method of co-ordinates, the discussion of simple harmonic 



motion and its application to the pendulum, and the 



method of finding moments of inertia. 



NO. 1092, VOL. 42] 



Several new examples have been fully worked out for 

 the purposes of illustrating the methods of solving 

 problems graphically, and some additional examination 

 papers have been given. 



At the beginning of the book tables of relative density 

 and of the English and French measures will be found, 

 and the work concludes with a newly added index. We can 

 only repeat what we said formerly, that this is a book to 

 be thoroughly recommended. W. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. ] 



The Pilcomayo Expedition. 



In view of the notice in the Times this week of the 

 collapse of the Pilcomayo Expedition, the inclosed extract from a 

 home letter of Mr. J. Graham Kerr, Naturalist with the Expe- 

 dition, may be of sufficient interest for publication in Nature. 

 The letter was received in Scotland on September 2. It con- 

 tains no mention of Captain Pj^e, and must have been written 

 before his death as recorded in the Times. The letter bears 

 out the Times account of the difficulties encountered by the 

 Expedition, and that the Pilcomayo is not likely to become a 

 trade water-way ; but it does not foreshadow disaster such as the 

 Times account suggests, and it gives hope that the other 

 members of the Expedition may not have shared the fate of 

 Captain Page. Isaac Bayley Balfour. 



September 27. 



" s.s. 'Bolivia,' Rio Pilcomayo, lat. 24° 25' S., long. 58° 40' W., 

 " Tuesday, June 3, 1890. 

 " We entered the Pilcomayo on March 12, therefore we have 

 been 3 months on the river. We have managed to penetrate 

 about 300 miles by river in that time, but owing to the extra- 

 ordinary tortuosity of the Pilcomayo, our distance in a straight 

 line from Asuncion I don't suppose is more than, if it reaches, 

 100 miles. The river is very disappointing from the points of 

 view of aesthetics, botany, zoology, geology, and anthropology. 

 As regards the first, the scenery in the lower reaches is certainly 

 beautiful, but of a type of beauty which soon palls upon one, 

 and becomes intensely monotonous. The scenery is very much 

 that of a sluggish flowing river at home. When we first en.- 

 tered the river, I was amazed at its small size — only about 50 

 yards in width. Up here it seldom reaches 20 yards, and is 

 frequently not more than 10, and there is scarcely any water in 

 it at all. For the last two months we have got forward not 

 more than 10 leagues, at the very outside, and what little we 

 have done has been by building dams, letting the water accumu- 

 late, and so getting forward for a short distance, when another 

 dam was built, and so on. The larger steamer, the General Paz, 

 we had to leave far down the river. The military detachment 

 whom we had left a few miles down was discovered the other day 

 to have flown, their provisions, no doubt, having run short. We 

 brought a corporal and two men on with us. The other day, 

 however, one of these deserted, and has, no doubt, either gone 

 over to the Indians or been killed by them. To return, how- 

 ever, to the scenery. Here, and for a long distance down, we 

 have had a type of scenery which is to be found in very few 

 parts of the world — that of an immense palm forest, covering 

 thousands of square miles. It consists typically of a perfectly 

 level plain clothed with breast-high grass, over which are closely 

 studded palm-trees with large fan-shaped leaves ; all around, 

 far as the eye can reach, an interminable vista of palm-trees, 

 varied only by an occasional clump of brushwood, or near the 

 river by a small patch of forest. In no way is the aspect of 

 nature suggestive of the tropics here, i.e. when one has got over 

 the first impression induced by the palm-trees. The Gran Chaco 

 is in fact an immense wilderness. Large game occurs only in 

 small numbers. I have managed to get only a couple of 

 peccaries, and no one else has shot any large game. I have not 

 even got a tiger yet, and have only once had anything approach- 

 ing an adventure with one. Other adventures we have had 

 absolutely none. Intense monotony and uninterestingness are 

 the chief characteristics of the river. Botanically speaking, it is 



