ESSAYS, &c. 
ON 
NATURAL HISTORY. 
REMARKS ON PROFESSOR RENNIE'S EDI- 
TION OF MONTAGU'S ORNITHOLOGICAL 
DICTIONARY. 
" It is admitted by all the naturalists already quoted, that 
the nest in question (grebe's) is built on moist ground, if not 
actually touching the water, and that part at least of the mate- 
rials consist of moist water plants. Now, it is indispensable to 
hatching, that the eggs be kept at a high temperature, and not 
be suffered to cool for a moment. The natural heat of the 
bird itself is sufficient for this purpose, without the heat of fer- 
mentation, erroneously supposed by Pennant ; but if she quits 
them for a moment, to go in pursuit of food, or to withdraw 
the attention of an intruding water-spaniel, or a prying natural- 
ist, their near vicinity to moist plants, or to water, would cer- 
tainly prove fatal to the embryo chicks. In order, then, to 
prevent the brood from being destroyed by cold, the careful 
bird covers the eggs with a quantity of dry hay, to keep them 
warm till her return." 
When the worthy professor wrote the above- 
quoted passage, I am sure that he had not the least 
doubt but that it was correct. Nine tenths of his 
readers would be of the same opinion with him. 
