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105
Report of the Medical Officer (Education).
Figure 2.—Shooter' Hill Open Air School.
Heights and weights, two boys born 1900, to shew
seasonal variation, also London Elementary School
standards without respect to season.
eight boys of various ages present the last two years.
D, is the average values for 14 girfe of various ages
present in 1910 and 1911, E gives four girls present
for three successive years, 1909, 1910 and 1911.
The features of these composite curves are equally
demonstrated by the curves either for children
born in specific years, or for individuals. There is
a rapid increase in weight whilst in attendance at
the school, with a slackening or even loss of weight
in the interval when the school was closed in the
winter.
Studying individual cases, the two boys
born . in 1900 who attended ShooterVhill 1908—
1911, can be taken. Figure 2 shows their average
weight by thick lines and heights by thin lines.
The increase of weight was mostly during school
time, with a retardation when the school was not
held. The regularity of this alteration is seen
through all the groups and in individuals, unless a
child is actually going down hill from tuberculosis
or has incidentally been thrown back by surgical
operation or acute illness.

At first the effect of the open-air school as regards increase of weight seemed wonderful, children
gaining at about double the rate of those in the ordinary schools. On the other hand, it is to be noticed,
as seen in the Figures 1, 2 and 3, that whilst the increase of weight slackens in the winter period,
there is, if anything, an acceleration of growth in height. This suggests a seasonal variation in growth
of stature and increase of weight. Fortunately some years ago measurements had been made to
ascertain standards for London school children ; from these, annual rates of growth can be deduced.
These rates, however, being annual, any seasonal variation is obliterated. Regular measurements of the
same individuals at periods of a month are required in order to determine this seasonal variation if it
exists, as it may be a factor of some importance in investigations in the future. At present, ignorance
of the amount of such variation makes the comparison of the figures existing for growth of children
in the open-air schools with that of normal children of doubtful value. The increase in weight of 12
children present during three successive years at Shooter's-hill amounts to 3-17 per cent, weekly,
normal children at these ages growing at an average annual rate of .185 per cent, weekly.
This comparison, however, includes two periods of the open-air school at the beginning and end
which, with the existence of a seasonal variation, would be unjust. If the increase of weight is
reckoned from the opening of the school in 1909 till its opening in 1911, the average is .257 per cent,
weekly ; if reckoned from the close of the school in 1909 till its close in 1911, the rate is .181 per cent,
weekly. The mean of these gives .217 per cent, weekly gain for the open-air children in two years
as against a normal .185 per cent. gain. On the other hand, 30 normal boys in the ordinary school at
Cator-street, during the 26 weeks, including the summer of 1911, gained weight at the rate of .326 per
cent, weekly. Whilst at Kensal House, 10 weeks of the summer showed a rate of .48 per cent, against
10 weeks' winter rate .20 per cent.
These considerations as to a seasonal variation of growth are borne out by a few observations
which have been previously recorded elsewhere, although their interpretation has not always been
taken as due to this supposed seasonal variation.
Thus Wretlind, in Gothenburg, tried to show that children grew much faster during the three
holiday months of summer than in the rest of the school year, which, indeed, was stated of the holiday
school at Kensal House this year. Wahl, in Denmark, in an institution for girls weighing on 1st April
and 1st October, found that the increase of weights of the summer half-year were one-third greater than
in the winter six months. He noted somewhat similar growth in children who did not attend school.
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