viii PREFACE 
Magazine of the Royal Scottish Geographical Society. 
These maps consist of two series. In the first series 
(Volumes III. and IV.), the contours of depth in the lakes 
are shown in shades of blue, and the contours of the height 
of the surrounding land are shown in brown shades of 
colour; in the second series (Volumes V. and VI.), the 
contours of depth are shown in shades of blue, the brown 
shades on the land being omitted. 
In addition to the bathymetrical maps, there are also 
a few maps showing the surface geology, the rainfall, and 
other physical features of some of the districts. 
These maps have all been prepared and printed by 
Dr J. G. Bartholomew, and we desire to express our in- 
debtedness to him for the care with which these have 
been produced, and for his assistance and advice in many 
directions. We are also indebted to INIessrs G. Cornwall & 
Sons, Aberdeen, for their assistance and advice with regard 
to the binding of the maps, and to Messrs Neill & Co., Edin- 
burgh, for their advice in connection with the letterpress. 
We feel confident that the whole investigation has 
resulted in very substantial contributions to knowledge. 
Some of the observations — those regarding the temperature 
seiche, and the variation of the viscosity of the water with 
temperature, for example — throw much light on obscure 
oceanographical problems. Most of the observations 
could, with advantage, have been carried further, by means 
of improved instruments and methods suggested during 
the progress of the work, but it was found necessary to 
terminate the survey, at least in the meantime, and to 
review what had been accomplished. We are conscious 
of many shortcomings. 
In conclusion, we tender our best thanks to all who 
have assisted us in carrying these investigations to a 
successful conclusion. 
JOHN MURRAY. 
LAURENCE PULLAR. 
Challenger Office, Edinburgh, 
February 1910. 
