Circumstances in connection with the recent census have again directed my attention to the laws which govern human life. I have long been of the opinion that the old ideas that birth rates and death rates had no biological relationship beyond the obvious ones, that many infants mean more deaths, etc., usually found stated in public health text books, were based on a very imperfect induction. On one aspect of this I published a paper a number of years ago in the Transactions of the Royal Philosophical Society of Glasgow (1), and last summer Sir Shirley Murphy(2) read a paper on another aspect of the same subject before the Sanitary Congress held at York. But I have hitherto refrained from publishing theories because I believe that until quantitative measures are applied no scientific results worthy of discussion can be obtained. Now that such seem to be possible, I propose to discuss in a series of papers the different relationships which I have investigated. No mathematics will be introduced in the earlier papers, but the results of all will be summarised and dealt with in their mathematical and physico-chemical relationships in a concluding communication. The first paper relates to the connection between the “corrected” death rates and the “true” death rates as found by constructing a life table.