1902 The Field NahiralisVs Library 233 



indicated above. For the descriptive portion we have nothing but 

 praise. The types are clearly described, and definite instructions given 

 for dissection and observation, whilst the student is aided in his reading 

 by the names of organs, (S:c., being printed in bold type. Teachers will 

 find this a useful book for students of scientific or medical courses of 

 invertebrate zoology. 



The Watkins Manual of Exposure and Development. By 

 Alfred Watkins. London: Geo. Houghton & Son. Price is. net. 

 Mr Watkins, who is president of the Herefordshire Photographic 

 Society and a member of the Woolhope Field Club, has given his 

 readers in this little book a most practical and handy manual of instruc- 

 tion in all the difificulties that beset the amateur photographer. The 

 author is well known as the introducer of two widely used methods of 

 exposure and development, and those who have had the pleasure of 

 seeing his own photographic work, as we have had, will be glad to have 

 the practical experience of a master of the art reduced to such a con- 

 venient compass. Definite instructions are given on those three im- 

 portant points : How long to expose, How long to develop, and How 

 long (or how much) to tone ; and the photographer who carefully 

 attends to the warnings and advice in this book cannot fail to find his 

 work much improved, and will have the gratification of seeing his 

 greatest difficulties vanish. We heartily commend ' The Watkins 

 Manual ' to all field naturalist and other photographers. 



Bird -Hunting on the White Nile, By Harry F. Witherby, 

 F.Z.S. London: 'Knowledge' Office. Price 2s. 6d. 

 " The journey, of which this little book forms a narrative, was under- 

 taken for the sole purpose of endeavouring to add to our knowledge of 

 the birds and beasts of the Soudan." A very pleasant narrative it is, 

 but by no means confined to birds and beasts, for there are many 

 interesting details given of the customs of the natives also. Mr 

 Witherby adds useful information on the Game Laws of the Soudan, and 

 instructions as to the , kind of photographic apparatus necessary for 

 success in that climate. The illustrations are from photographs by Mr 

 C. F. Camburn, who accompanied the author, and by Mr A. F. R. 

 Wollaston, who visited the Soudan in 1901. Most of the chapters 

 appeared in ' Knowledge ' last year, and to these have been added 

 appendices of the birds and mammals seen and collected. 



The Naturalist on the Thames. By C. J. Cornish, F.Z.S. Lon- 

 don : Seeley & Co. Price 7s. 6d. 

 Mr Cornish is well known to field naturalists of the Thames district 

 as a writer on the varied natural history of that locality. Much of the 

 matter of this book has previously appeared in the 'Spectator,' 'Coun- 

 try Life,' and the ' Badminton Magazine ' ; but as the articles were 

 written with a view to publication in the form of a commentary on the 

 natural history and character of the Thames Valley as a whole, the 

 work does not suffer from the lack of continuity often associated with 



