We are, for obvious reasons, forced to gauge the prevalence of phthisis in asylums by its mortality. Several questions at once present themselves:

What is the mortality from phthisis at the present time in the British Islands ? What is the mortality from phthisis in the asylums of the British Islands ?

Are these mortalities diminishing or increasing ? And what relation do they bear to one another ?

It is easy to propound these questions; it is extremely diffi cult to properly appraise the available data. For, first, if it be desired to compare the mortality from phthisis of asylum inmates with that of the general population, the comparison must be made on the basis of the ratio, in each case, of the annual deaths from phthisis to the average populations in volved. In other words, the phthisis death-rate, and not the percentage of deaths assigned to phthisis, must be estimated.