458 



NATURE 



[June 17, 1909 



more observations on this point. The hawk-moths men- 

 tioned by one correspondent arc scarcely sufficiently 

 common to >prvc as the usual pollinating agencies, and 

 the dipterous insect (apparently a Volucclla) arrived in too 

 frapmentary a condition for identification. The Bombi 

 certainly visit these flowers, but the vague " bee " used 

 in the book under review would certainly lead to confusion 

 with the true honey-bee, which is not known to visit 

 primulas. I may add that in the Manchester Museum 

 there is a series of insects taken by Prof. Weiss on the 

 primrose. No moths arc included amongst them. 



The Reviewer. 



An Optical Phenomenon. 

 Is your correspondent " V. P." (N.atlre, June 3, p. 398) 

 perfectly sure that there is not in the glass pane in ques- 

 tion one of those flattened oval air bubbles so common 

 in window glass, which he may have overlooked? The 

 phenomenon of the dark disc of shadow with the bright 

 edge so exactly corresponds with the effect produced by 

 these common flaws in glass that, in spite of his 

 assurances, I cannot help suspecting that he may have 

 misjudged the angle of incidence of the sun's rays. A 

 window is before me as I write which presents identically 

 the same phenomenon, and I was nearly being misled 



SPRUCE'S TRAVELS IN SOUTH AMERICA.' 



DR. ALFRED RUSSEL WALLACE has rendered 

 a great service to the scientific world, not 

 only in having consented to rescue from oblivion 

 the account of .Spruce's remarkable travels, but also 

 by the admirable way in which he lias edited the 

 nianuscripts jjlaced in his charge. Spruce's journal, 

 which forms the substance of these volumes of 

 about 1040 p;ij,'es, has been carefully edited and 

 considerably condensed. Passages of no particular 

 interest have been omitted, and short summaries by 

 the editor take their jilace. Several letters to Sir 

 William Hooker, .Mr. Hentham, and personal friends 

 have been inserted which carry on the narrative 

 and give a more life-like impression of Spruce himself. 

 These letters, which are keenly alive and full of 

 human interest, form some of the most interestinpf 

 portions of the book. Those to Mr. Bentham show 

 the ardent botanist fired with enthusiasm for his 

 work, whilst those to his friend Mr. Teesdale reflect 

 the character of the man himself, and give a vivid 

 picture of the every-day occurrences and of the perils 

 which he experienced. 



I.— Ctrro Duida ((Eooo fe«l), from ihe Cross near the Village of Esmeralda. Looking nc 



Botanist on the Amazon and Andes," vol. 



rth. (R. Spruce, December, 1853.) From " Notes of a 



until, with a pencil point laid on the pane, I tracked the 

 shadow to its source, which was much higher up on the 

 window "than I should have judged. 



Charles E. Beniiam. 

 28 Wellesley Road, Colchester. 



Dew-Ponds. 



In the recent correspondence on this subject several rival 

 theories have been put forward to account for the supposed 

 fact that certain ponds situated on the tops of hills have 

 a plentiful supply of water. It seems to me that no satis- 

 factory solution of the question can be expected until much 

 more definite data are at hand. 



What is w;anted is a detailed, contoured survey of a 

 typical " dew-pond " with its drainage area, and a year's 

 observations of the height of water in it, an estimate of 

 the number of cattle using it, rainfall and hygromctric 

 observations in the neighbourhood, and a section .showing 

 the construction of the bed of the pond and adjoining 

 slopes. If someone interested in the question and resident 

 in the neighbourhood of one of these ponds would under- 

 fake the work, it would be of far more value than twice 

 the labour spent in founding th.'Ories on insufficient data. 



Wirksworth, June 12. L. GiBBS. 



NO. 206S, VOL. 80] 



At times the reader is inclined to complain of an 

 occasional want of continuity and of abrupt changes 

 of subject, but such blemishes are not common, and, 

 owing to the necessity for condensation, could perhaps 

 hardly have been avoided. 



The first volume, coverings the period from July, 

 1849, to January, 1855, deals with Spruce's travels 

 on the .Amazon and Rio Negro, including a journey 

 along the Casiquiari and to the Orinoco cataracts. 



The second volume opens with the account of the 

 voyage from Manaos to Tarapoto, and continues 

 his travels in the eastern .Andes of Peru from that 

 place, his excursions in Ecuador and in the Cin- 

 chona forests, and his last years on the western side 

 of South America. There are also botanical and his- 

 torical notes, which conclude with a highly exciting 

 story of a hidden treasure of the Incas. The period 

 spent in Soutli .\mcrica covered by this volume is 

 from March, 1S55, to .April, 1864. 



1 *' Notes of ft Botanist on the Amazon and Andes." By Richard Spruce- 

 Edited and condensed hy Dr. Alfred Russel Wallace, O.M , F.R.S., with a 

 Ttiographical Introtlucrion, Portraii, 71 illustrations and 7 maps. 1 vols. 

 Vol. i., pp. lii + 518; vol. ii., pp. xii + 543. With a Glossary of Native 

 Names and Index. (London: Macmilfan and Ca, Ltd., 1908.) Price- 

 311. net. 



