There are two volumes[138] which, as Professor H. S. Pritchett well says in an able article on pension literature (_Fifteenth Annual Report of the Carnegie Foundation_, 1920) “mark the close of one period in the history of pensions and the beginning of a new scientific one.” The most difficult question is the method of calculating the amount of superannuation benefits. If the basis is the flat rate, this is simple; but if it is the average of the salary given during the last five or ten years, or during the whole period of service, the difficulty in determining the amount of actual contributions to yield the prospective benefit becomes very great. Teachers’ salaries are, especially now, very unstable. A pension system based on anticipated pay leaves too much in suspense. It is difficult to provide pensions on a subsistence basis, which also bears some relation to final salary. If the pension is too high, there is temptation to retire too early; if it is too low, to retire too late. Ultimately, too, teachers must be able to migrate without loss or change of status and this would involve reciprocity between different cities and even states. In New York, before the new system went into effect in 1921, there were 2,000 different rates; and in Pennsylvania, 86. The new system of New York, which developed because the old one had settled into bankruptcy, although optional for teachers appointed before 1921 is compulsory for those appointed after and the pension is to consist of half the average salary during the last five years; the payment is not to exceed $800 and this will be paid after 25 years of service. The old view which held that the very word “pension” suggested a cripple and real manhood would compel everyone to lay by for old age, and which flattered those who entered their profession in youth with the hope that in old age they “might be permitted to sun themselves on the veranda of a state poorhouse,” has entirely passed away. But pensions are no longer considered as a form of charity or a form of paternalism, or even as a reward for service. They only demand of the teacher the same thrift as do savings and their proper function is to secure efficiency of service and they should be regarded “as a condition of service just the same as a salary.” Most of even the best recent systems, like that of the District of Columbia and the Y. M. C. A. officers’ pension plan, which is just about to go into operation, are a compromise between the old and the new ideas. The same is true of civil-service pensions in New York state and city.