Page:Popular Science Monthly Volume 42.djvu/73

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M. Inaudi, faithful to the processes of his infancy, manages them with surprising dexterity. He has perfected, developed, and enlarged them, but has not changed their nature.

The basis of his calculations is multiplication; even in dividing or extracting the square root, he multiplies. He makes a series of multiplications of approach. In a division, for example, he finds the quotients by groping; seeking and trying a number which, multiplied by the divisor, will produce the dividend.

He follows a course in multiplication which is peculiar to him. If more than one figure is included, he does not perform the process all at once, for he has no more extended multiplication table than ours; but his method consists in decomposing a complex multiplication into a series of simpler ones. If he is to multiply 325 × 638, M. Inaudi calculates thus:

300 × 600 = 180,000 300 × 8 = 2,400
25 × 600 = 15,000 25 × 30 = 750
300 × 30 = 9,000 25 × 8 = 200

In short, he makes six multiplications instead of one. He begins on the left, multiplying, therefore, the figures of the highest value. In other cases he changes the data around. Instead of multiplying by 587, he multiplies by 600 and then by 13, and subtracts the second product from the first. The observation of M. Inaudi brings a new factor to the theory of partial memories. It is usual to employ the word memory in a general sense to express the property, common to all thinking beings, of preserving and reproducing the impressions they have received; but psychological analysis and a large number of facts in mental pathology have shown that memory should not be regarded as a sole faculty, having a distinct seat; in the final analysis, memory is a group of operations. There exist, according to the report of the committee of the Academy, partial, special, local memories, each of which has its special domain, and which are so independent that one of them may be enfeebled, may disappear, or may develop to excess without the others necessarily presenting any corresponding modification. The older psychologists missed this truth. Gall was probably the first to assign its proper memory to each faculty, and founded the theory of partial memories. It is at the present time supported by multiplied facts, a large number of which have been furnished by M. Taine. He has cited, among others, the cases of those painters, designers, and statuaries who, after having carefully regarded a model, can make its portrait from memory. They supply fine examples of the development of visual memory. Then there are cases of musical memory. The subject has been revived of late years in the study of diseases of language. Cases have been cited of patients in whom the single memory of language, very limited and special, is abolished, while