M. Beeton and K. Pearson 
51 
reticence as to the age of women, even at death, observed by the couijjilers of 
peerages and family histories. The limitation as to adult lives arose also from the 
small interest exhibited by the same compilei's as to the exact age at death of 
infants ; indeed members of the family dying as infants often escaped any record 
at all. The difficulties thus referred to were finally overcome by working solely at 
the pedigree records of members of the Society of Friends. Through the kindness of 
Mr Isaac Sharpe, a great mass of material in the form of family histories and other 
recoids at the central offices of the Society, Devonshire House, E.G., was placed at 
Miss Beeton's disposal. Further material of a valuable nature was provided by 
the Secretary of the Friends' Provident Association, and we have cordially to thank 
both these gentlemen for their ready assistance and their invariable courtesy. 
Miss Beeton working solely at the material thus provided was enabled to form 
fairly extensive tables for the inheritance of longevity in the female line, and also 
with somewhat less extensive data for the deaths of infixnts* to form some appre- 
ciation of what we have elsewhere termed the inheritance of " brachybiotyf." 
The whole of the material was extracted, tabled, and the constants calculated by 
Miss Beeton |, and the work has been one demanding very considerable labour 
and continued caution. My function has been solely consultative in cases where 
difficulties in dealing with the raw material or in the calculation of the constants 
arose. 
(2) With regard to the tabulation of the data we had found a five year unit 
of grouping sufficiently close in the case of adult lives. I do not think any serious 
error is introduced by grouping at the mid-point of five years all the deaths 
occurring in a five year period. But the matter is very different when we come 
to deal with individuals dying as minors; we cannot possibly group them together 
in five year periods, and if we were to do so, then we could not centre the group at 
the mid-point of the period. The avei'age age at death of children, for example, 
dying in the first five years of life is certainly not 2*5 years, it is much less. It 
may be asked why we did not take the year as the unit of life. The answer is 
twofold : Had we done so we should, treating all lives togethei', have had to 
construct a correlation table with over 10,000 compartments! This is practically 
impossible on account of the labour involved. In the next place the mortality 
curve is not simple but compound, and the causes of infantile and adult mortality 
are largely different, — there is, as we have said, a tendency to brachybioty as well 
as one to longevity. Tlius we have separated our tables in the case of those 
dying as adults and those dying as minors, using a five year period for the 
classification of the first and a one or a two year period for the classification of the 
second§. But here again a further difficulty arises. The actual days of birth and 
* The whole material available was exhausted, and this must explain why in certain cases we 
have stopped at less than 1000 cases, 
t li. S. Proc, Vol. 65, p. 299. 
J The whole of the calculations were afterwards corrected or verified by Dr Alice Lee, and we 
have to thank her most heartily for her aid. 
§ Another reason for this division is also to be found in the fact that many infantile deaths are 
4—2 
