Among the many curious facts relative to the duration of human life which have resulted from the persevering inquiries of persons interested in Life Assurance Offices, one very essential question appears to me to have been left undecided—namely, whether, and in what degree, a diet of vegetable food alone increases the length of life. The Vegetarian Society of Manchester pretend, not only that pure vegetable diet renders man almost exempt from many of the most fatal complaints to which we are subject, but also, that it has actually prolonged the average duration of human life. To this question I beg leave to call the attention of your readers: I should like to see it fully investigated and developed. My attention has been directed to the effects of different sorts of food on different kinds of constitution for many years past, and the conclusion to which I have come is certainly in the highest degree favourable to the views of the Society alluded to, particularly as respects longevity, to which the pure vegetarian diet seems to be particularly favourable. Now this circumstance, of which I have not the least doubt, brings the question of diet immediately into the category of facts which are the proper objects of inquiry for all Assurance Companies. Having thus ventured to call the attention of these Companies to the subject, I shall take the liberty of submitting the following facts and experiments to the notice of your readers: they are the result of nearly half a hundred years' observation and experience, made in various countries of Europe.