PREFACE. 1X 
communicate the results of their observations to the 
world without waitmg for a period (never perhaps to 
arrive) when they may themselves have the credit of 
completing and perfecting them. It is better, whilst 
the freshness of recollection is undimmed, and the mind 
is in a position to draw a correct parallel between older 
and quite recent observations, and thus to give our 
descriptions the necessary development, to throw into 
them whatever there may be of value in our peculiar 
experience or habits of investigation, and frankly to 
invite our fellow-labourers to do in our stead what we 
would gladly have done but for some inevitable want 
of health, leisure, or opportunity. Were this course 
more generally followed in the sciences, both of obser- 
vation and experiment, I am persuaded that by grasping 
at less we should attain more—even in personal repu- 
tation—and should unquestionably advance the interests 
of knowledge.” 
Norfolk Crescent, Bath, 
November, 1854. 
