February 22, 19 12] 



NATURE 



545 



manner in which the author quotes the various find- 

 ings of the Commissioners, with whose work he is 

 naturally thoroughly intimate. Considerable space is 

 (Itvoted in the opening- chapters to a historical survey 

 of the subject, toerether with a rdsume of the various 

 laws enacted to deal with questions of public health, 

 river pollution, &c. Later, such questions as drainage 

 area, water supply, sewerage system, rainfall, 

 variation in rate of flow of sewage, &c., all of which 

 influence in some degree the ultimate scheme of puri- 

 fication, are dealt with in a very complete manner. 



Under the head of preliminary processes the author, 

 of course, deals with the various methods of tank 

 treatment. It is, however, unfortunate that in a work 

 of this character passing *fb'ference only is made to the 

 recent work in regard to the extension of the original 

 idea of septic tank treatment. It would have been 

 interesting, e.g. to have had the author's views on 

 the Emscher tank of Imhofl", which at the present 

 lime is apparently creating a very favourable impression 

 amongst Continental and American engineers. 



Where difficulty is experienced in disposal of the 

 tank sludge, it is obviously important to reduce the 

 quantity produced to a minimum. The above tank 

 is designed with this object, by allowing the accumu- 

 lated sludge a maximum period for fermentation out 

 nf contact with the sewage passing through, and it 

 i- claimed that not only is there a considerable amount 



actual destruction of the organic matter, but that 

 ■ i. resultant sludge is of high density with conse- 

 quent further diminution of volume to be dealt with. 

 On the other hand, where the sludge can be readily 

 I disposed of without nuisance, it is very doubtful 

 whether the increased expenditure on tank construction 

 would be justified. 



In connection with the question of tank treatment, 

 the author's statement that nitrogen and oxygen are 

 evolved in the septic tank requires correction. The 

 ' conditions prevailing do not allow of the evolution of 

 nx\gen, and in the absence of nitrates in the sewage 

 it is more than doubtful whether nitrogen is actually 

 evolved. Nitrogen is usually found in septic tank 



-<s, but in all probability it is derived from solution 



the sewage and not as the result of any fermenta- 

 tive action. The chapter on sludge disposal is well 

 written and comprehensive; reference, however, could 

 with advantage have been made to the possibility of 

 the recovery of grease from sludge, or of use in 

 specially constructed gas producers. 

 The author's intimate acquaintance with the repre- 



lative English sewage farms has enabled him to 



Ideal with the question of the purification of sewage 

 on land in an excellent manner. Unfortunately the 

 number of places where such treatment of sewage is 

 possible in England is rapidly diminishing. When 

 ! considering the question of treatment of sewage on 

 contact beds and percolating filters, the author follows 

 the lines laid down by the Royal Commission, and in 

 the chapters dealing with this part of the subject 

 elaborate quotations from the various reports of the 

 I Commission are given. It is to be observed that as 

 I regards the engineering side of the subject, the author 

 I doubtless has been to a large extent responsible for 

 ! the conclusions arrived at by the Commissioners. 

 NO. 2208, VOL. 88] 



The importance of the remarks on p. 229, in regard 

 to the construction of feed carriers, cannot be too 

 strongly emphasised. The existence of channels 

 which can only be emptied by extensive pumping 

 operations is certainly to be avoided, on account of the 

 trouble arising from the secondary decomposition of 

 the sludge which periodically accumulates. 



The value of the work is increased by the number 

 of examples of works in operation, together with plans 

 and results of treatment, although a more representa- 

 tive works illustrating contact-bed treatment might 

 have been selected. The book can be recommended 

 to sanitarians as affording a good general survey of 

 the subject from the engineering point of view, and 

 more particularly as being an admirable handbook 

 to the voluminous reports of the Royal Commission 

 on Sewage Disposal. Edward Ardern. 



VERTEBRATES OF TWEED. 

 A Fauna of the Tweed Area. By A. H. Evans. Pp. 

 xxviii + 262. (Edinburgh: David Douglas, igii-) 

 Price 30s. 



THIS is the eleventh volume of Mr. J. .\. Harvie- 

 Brown's well-known "Vertebrate Fauna of Scot- 

 land," and brings the series within sight of com- 

 pletion, four areas (Forth and Clyde, Sohvay and 

 Dee) remaining to be dealt with. Mr. A. H. Evans is 

 to be congratulated on the success with which he has 

 dealt with the fascinating area of "Tweed " and sus- 

 tained the high traditions of the series. In his labour 

 of love he has been loyally helped by Mr. George Bolam, 

 Mr. William Evans (who is treating of the Forth 

 area), Mr. George Muirhead, Mr. Abel Chapman, and 

 other well-known observers, not forgetting the editor 

 himself. The beautiful illustrations which adorn the 

 text are mostly due to photographs by Mr. William 

 Norrie, of Fraserburgh, whose work has enhanced 

 the value of previous volumes. They bring the habi- 

 tats depicted very vividly before the eye, most of all 

 when pleasant memories are already there. 



"Tweed" is a scientifically natural area, a vast 

 amphitheatre, facing the German Ocean, surrounded 

 on three sides by hills of considerable height, and 

 watered bv the river Tweed and its tributaries. It 

 includes considerable variety of habitat— the hills, the 

 sea-cliffs, the rivers, th. moors, the woods, and the 

 fertile plains, and the taun.i is correspondingly diverse. 

 In his " Introduction " Mr. Evans directs attention to 

 some of the features of peculiar interest. Thus it is 

 still the haunt of some of our scarcer mammals, such 

 as the badger and the great grey seal ; and as regards 

 birds, its peculiar interest is in connection with exten- 

 sion of range northward or southward. The nighlin- 

 i;al.' uas once identified within the limits, the nuthatch 

 has been known to nest, the wryneck and the green 

 woodpecker have occasionally l>ocn seen- " these birds 

 being here approximately at the northernmost point 

 of their range in the United Kingdom." "Of equal 

 interest are those birds which find in the Tweed area 

 their extreme limits to the southward, or at least have 

 not been known to extend far beyond it in recent 

 times." Thus a golden eagle was shot in 1877 on one 

 of the Cheviots, where in earlier days it used to have 



