546 



NATURE 



[April 26, 1877^ 



between the Skiddaw slate and the overlying Volcanic 

 Series, and the existence of the chain of faults which every- 

 where separates the two groups. Mr. Ward relies on the 

 fact that beds of volcanic ash occur on the upper part of the 

 Skiddaw slate. This shows that volcanic activity began 

 before the deposition of the Skiddaw slate was completed, 

 but it scarcely proves that no upheaval and denudation 

 attended the commencement of the volcanic outbursts. 

 Volcanic activity and elevation are so intimately con- 

 nected that it may well be that the early discharges were 

 the heralds of an upward movement of the rocks. The 

 author indeed admits thus much, and believes that slow 

 upheaval did attend the advent of volcanic activity, and 

 that the bulk of the volcanic products are terrestrial. We 

 should be inclined to go further, and to suggest that a 

 long period may have followed the first volcanic out- 

 breaks, during which the Skiddaw Slate was crumpled up 

 and brought within the range of atmospheric denudation. 

 Any volcanic deposits formed during this interval would of 

 course be removed by denudation. By the time the volca- 

 noes had reached their full growth, a land-surface, diver- 

 sified by hill and valley, may have been produced, and when 

 the volcanic products were showered down on this uneven 

 floor, heaps of ash and sheets of lava would every here 

 and there abut against banks of Skiddaw Slate, in a 

 manner that produces to us a deceptive appearance of 

 faulting. We give this hint merely for what it is worthy 

 and have no wish to throw any doubt on the possibility 

 of the boundary being such as the map represents it to 

 be ; indeed, instances about which there can be little 

 doubt might be quoted, where two groups of rocks are 

 parted by just such a jagged line of faults as that which 

 Mr. Ward has drawn in the present case. 



The book is liberally illustrated by maps and sections, 

 and the bibliographical list of works relating to the 

 geology of the district is a most welcome addition. 



We cannot but feel that a great mistake has been 

 made in the map which the memoir is intended to illus- 

 trate. As a typographical piece of work it is unsurpassed, 

 but it is its excellence in this respect that makes it 

 unsuited for geological purposes. The reliefs of the 

 surface are admirably brought out by the hill shading, but 

 in order to produce the desired efiect, the hatching 

 has been made so dark that in many places it is difficult, 

 if not impossible, to distinguish the geological colouring 

 and signs. The Ordnance Survey issue in the northern 

 counties another set of one-inch maps, with contour-lines 

 in the place of hill-shading, and had one of these been 

 employed to receive the geological colouring, the very 

 serious difficulty just mentioned would not have arisen. 

 We have no hesitation in saying from actual experience 

 in the use of both classes of maps, that had plain copies 

 been used, the value of the map would have been well- 

 nigh doubled. 



Before concluding we would remonstrate with the 

 author on his italics ; the book bristles with them, till it 

 reminds one of a school-girl's letter. This indiscriminate 

 use of emphasis destroys that repose which is one of the 

 chief charms of style, and in a very large number of cases 

 there is no necessity for it, for t'he meaning would be 

 perfectly clear without the adventitious aid of a variation 

 in the type. 



A. H. G. 



VENNOR'S '' ACCIPirRES OF CANADA'' 



Otcr Birds of Prey j or. The Eagles, Hawks, and Owls of 

 Canada. By Henry G. Vennor, F.G.S. With Thirty 

 Photographic Illustrations by W. Notman. 4to, pp. 

 i.-viii,, 1-154, plates i.-xxx. (Montreal : Dawson 

 Brothers ; London : Sampson Low and Co., 1876.) 



SO little is really known respecting the ornithology of 

 Canada that one cannot but welcome with great 

 satisfaction such a substantial addition to our knowledge 

 as has been given by Mr. Vennor in the present work. 

 As a geologist employed on the survey of Canada the 

 author has enjoyed unrivalled opportunities for studying 

 many of the birds in the field, and although the fulfilment 

 of his duties has prevented him from devoting his entire 

 attention to ornithology, yet he has evidently kept his 

 eyes open, and the work before us embodies the result of 

 thirteen years' observation. It is to be regretted that at 

 present Mr. Vennor has only written on the birds of prey, 

 and it is to be hoped that he will continue his labours on 

 the rest of the birds of Canada. The species themselves 

 included in the present work are twenty-seven in number, 

 and on all these very complete information seems to 

 be given respecting their distribution in the Canadian 

 dominion, including not only a r'estime of the hitherto 

 published facts, but giving also a large amount of new 

 information. Excellent accounts of the habits of the 

 birds are added, chiefly from the personal observations 

 of the author himself, and each article concludes with 

 the description of the species in which the colours of the 

 soft parts are always given ; this is a feature often 

 omitted by Messrs. Baird, Brewer, and Ridgway in 

 their recently-published " History of North American 

 Birds." Mr. Vennor does not include among the species 

 fully treated of, the Common Turkey Buzzard {Rhino- 

 gryplms anrea), which hardly extends to Canada in its 

 northern range, though it is a regular summer visitant to 

 " the extensive flats near Chatham and Lake St. Clair," 

 while further to the westward it occurs frequently on the 

 line of the forty-ninth parallel. Of the Barn Owl {Strix 

 flammed), Mr. Vennor says that there is no authentic 

 record of its occurrence in Canada, but we notice in Mr. 

 Bowdler Sharpe's paper on the " Geographical Distri- 

 bution of Barn Owls," published in Mr. Rowley's Orni- 

 thological Miscellany, that the British Museum contains 

 a specimen from the neighbourhood of Toronto, collected 

 near that city by Mr. James Whitely, who has resided 

 there for some years, and has sent many interesting birds 

 to this country. Other small points might also be alluded 

 to in which we think further consideration on the author's 

 part desirable, such as the relations between Falco candi- 

 cans and F. labradorus, Cij'cus cinereus and C. hiidso- 

 nius, &c. We are not disposed to quarrel with the 

 photographic illustrations to the book, which are excel- 

 lent specimens of photography, although this mode of 

 illustrating scientific works does not commend itself to 

 our fancy. At any rate, however, a good photograph i-^ 

 better than a bad plate, especially in a work like the pre- 

 sent, where the author's chief aim has been to give such 

 a figure as may render the identification of the species 

 more easy to the student, his object being, in his own 

 words, " a work of practical utility, not a mere exhibit^ 

 of pretty photographs." As a new worker in the vast fii 



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