Personal identification and description / Francis Galton.

  • Francis Galton
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: Personal identification and description / Francis Galton. Source: Wellcome Collection.

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    A curve drawn through their tops gives the upper boundary of the scheme ; the lines themselves are then wiped out, having served their purpose. If the base A B be divided into three equal parts and perpendiculars, C, D; E, F, be erected at the divisions between them, reaching from the base up to the curve, then the lengths of those Fic. 4, SCALE OF INCHES dl ocmu ee © me mt mn ae oe es ee ee ee ee to es es er rT A e1 C ce2 e1 E e2 B perpendiculars will be proportionate to the limiting values between the small and the medium group, and between those of the medium and the large group, respectively. The difference between these perpendiculars in the case of stature is about 2°3 inches. In other words, the shortest and tallest men in the medium class differ only by that amount. We have next to consider how much ought reasonably to be allowed for error of measurement. Considering that a man differs in height by a full third of an inch between the time of getting up in the morning and lying down at night; con- sidering also that measures are recorded to the nearest tenth of an inch at the closest, also the many uncertainties connected with the measurement of stature, it would be rash not to allow for a possible (I do not say “ probable”) error of at least + half an inch. Prolong C D, and note the points upon it at the distance of half an inch above and below D; draw horizontal lines from those points to meet the curve at d.1, d.2, and from the points of intersection drop perpen- diculars reaching the base at c.l, c.2. A similar figure is drawn at F.
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