Now comes a most extraordinary fact. Dr. Major Greenwood, [64] a statistician whose methods are beyond question, discovered that there was no real mathematical difference between the number of children in the "limited" families and the number in the unlimited families. In both groups of families the number of children was smaller than the average family in the general population, and in both groups there were fewer children than in the families of the preceding generation to which the parents belonged. Dr. Greenwood states that this is _prima facie_ evidence that deliberate birth control has produced little effect, and that the lowered fertility is the expression of a natural change. Nevertheless, he holds that the latter explanation cannot be accepted as wholly proved on the evidence, owing to certain defects in the data on which his calculations were based. "I am of opinion that we should hesitate before adopting that interpretation in view of the cogent indirect evidence afforded by other data that the fall of the birth-rate is differential, and that the differentiation is largely economic. There are at least two considerations which must be borne in mind in connection with these schedules. The first is, that all the marriages described as unlimited may not have been so. I do not suggest that the answers are intentionally false, but it is possible that many may have considered that limitation implied the use of mechanical means; that marriages in which the parties merely abstained from, _or limited the occasions of_, sexual intercourse may have frequently entered as of unrestricted fertility." The above italics are mine, because, if that surmise be correct, it goes to prove that the restriction of intercourse to certain periods, which restriction the married may lawfully practise, is as efficacious in limiting the size of a family as are those artificial methods of birth control contrary both to natural and to Christian morality. Dr. Major Greenwood continues as follows: "In the second place, the schedules do not provide us with information as to when limitation was introduced. We are told, for instance, that the size of the family was five and that its number was limited. This may mean _either_ that throughout the duration of the marriage preventive measures were adopted from time to time, _or_ that _after_ five children had been born fertile intercourse was stopped. In the absence of detailed information on this point it is plainly impossible to form an accurate judgment as to the effect of limitation." There are, therefore, no accurate figures to indicate the extent to which birth control has contributed to the decline in the birth-rate. Section 3. AND TO CHARACTER OF OCCUPATION