Inquiries into human faculty and its development / Sir Francis Galton.

  • Francis Galton
Date:
1907
Catalogue details

Licence: Public Domain Mark

Credit: Inquiries into human faculty and its development / Sir Francis Galton. Source: Wellcome Collection.

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    Table II. Number of Families. * Number of Children, Factory. Agricultural. Factory. Agricultural. Within outline 541 436 903 778 Between outlines 375 476 1233 1562 Beyond ,, 84 88 545 571 li Total 1000 1000 2681 2911 C.—AN APPARATUS FOR TESTING THE DELICACY WITH WHICH WEIGHTS CAN BE DIS¬ CRIMINATED BY HANDLING THEM. [Read at the Anthropological Institute, Nov. 14, 1882.] I submit a simple apparatus that I have designed to measure the delicacy of the sensitivity of different persons, as shown by their skill in discriminating weights, identical in size, form, and •colour, but different in specific gravity. Its interest lies in the accordance of the successive test values with the successive graduations of a true scale of sensitivity, in the ease with which the tests are applied, and the fact that the same principle can be made use of in testing the delicacy of smell and taste. # I use test-weights that mount in a series of “just perceptible differences” to an imaginary person of extreme delicacy of per¬ ception, their values being calculated according to Weber’s law. The lowest weight is heavy enough to give a decided sense of weight to the hand when handling it, and the heaviest weight can be handled without any sense of fatigue. They therefore conform with close approximation to a geometric series ; thus— WR\ WR\ WR\ WR3, etc., and they bear as register-marks the values of the successive indices, o, 1,2, 3, etc. It follows that if a person can just dis¬ tinguish between any particular pair of weights, he can also just distinguish between any other pair of weights whose register- marks differ by the same amount. Example : suppose A can just distinguish between the weights bearing the register-marks 2 and 4, then it follows from the construction of the apparatus 1