154 Notes and Comments, 
issued by the Society, and it is proposed to do the work in a very 
comprehensive manner. In order that the scheme- may be 
carried through successfully it is necessary to enlist the co- 
operation of all who are interested in such work. Those who 
wish to help should communicate with the Secretary, Mr. A. 
Gilligan, the University, Leeds. 
DEW PONDs.* 
Mr. Martin has taken a considerable interest in these 
structures, and from time to time has contributed notes in 
different scientific journals on the subject. The present book 
is a summary of the information he has gathered together as 
to their age and history, theories, modes of construction, 
experiments and observation. By the illustrations given it 
Sheep watering at Upper Standson Pond. 
is evident that in the south of England dew-ponds are of 
much larger size and importance than the so-called dew-ponds 
on the Yorkshire Wolds. He states that when he commenced 
his experiments he had a strong leaning in favour of the theory 
of the replenishment of these ponds by dew, but he was soon 
led to abandon this idea, and, although there is evidence to 
show that considerable condensation takes place into high- 
level ponds other than rain, dew has, he submits, little or 
nothing to do with it. 
DEW PONDS ON THE YORKSHIRE WOLDS. 
Mr. Martin quotes the following interesting note by the late 
J. R. Mortimer :—‘ Perhaps no district of the same area 
contains more ponds than the Mid-Wolds of Yorkshire. These 
are partly ancient, partly modern. The latter can be numbered 
by hundreds, nearly all of which have been made during the 
last 150 years—mostly after the inclosures of the parishes. 
* History, Observation and Experiment, by E. A. Martin, F.GS. 
London: T. Werner Laurie, Ltd. 208 pages, 6s. Not dated. 
Naturalist, 
