and other trade risks; though if trade is bad there are fewer ships sailing and fewer goods in transit, though there may be more in the warehouses.
Insurance is a very complicated and difficult business, and the complications and difficulties reflect themselves in the accounts and balance-sheets published by the companies, especially those of the kind usually described as composite, because they usually carry on several different kinds of insurance business, the main divisions being life, fire, marine, employers' liability and sickness and accident.
All these different divisions require highly specialized skill, though the life department is now comparatively simple owing to the mass of knowledge that has been acquired, through more than a century of investigation and record, concerning the probabilities of the length of human life. Given the requisite medical skill to judge whether an applicant for insurance is sound in wind and limb—and a few other particulars—or how much allowance should be made for any weakness that may be detected, a skilled actuary can easily work out his expectation of life—barring accidents. Moreover, as the mortality tables on which the companies work are necessarily the result of past experience, and as improved sanitation, medical
