" Things being thus prepared," says the Doctor, " let a peg of the first set (with a plain triangular head) be fixed into the board ; and it. will acquire four different values, according to its position re specting the calculator. When its sloping side is turned towards the left, it denotes one, or the first digit ; when turned upwards, or from the calculator, it denotes two, or the second digit ; when turned to the right, it represents three ; and when turned down wards, or towards the calculator, it denotes four, or the fourth digit. Five is denoted by a peg of the second set (with a notched triangular head), having its sloping side, or hypothenuse, turned to the left ; six, by the same turned upwards ; seven, by the same turned to the right ; and eight, by the same turned directly down, or towards the body of the calcula ' tor. Niue is exnressed by a peg of the third set (with a square head) when its edges are divided to right and left ; and the same peg expresses the cy pher, when its edges are directed up and down.— When it is necessary to express a vulgar fraction, I place the numerator in the groove immediately above, and the denominator in that immediately be low the groove in which the integers stand ; and in decimal arithmetic, an empty hole in the integer groove represents the comma or decimal point. By similar breaks, I also denote pounds, shillings, pence, &c. : and by the same expedient, I separate, in divi sion, the divisor and quotient from the dividend. Coefficients and indices, in algebra and fluxions, are supplied upon similar principles." Various attempts have been made to supply the blind with tangible musical characters, or signs, by which their progress in the acquisition of an art which affords them sohgreat delight, and for which they are so peculiarly qualified, might be materially facilitated. We do not think, however, that these attempts have been attended with the same success, as in the case of the palpable arithmetic. In Tan sure's Mu.sical Grammar, p. 93., it is recommended, that the blind musician should be provided with a smooth board with ledges of deal glued on it at pro per distances, to represent the five lines of the musi cal staff; with such additional lines as occasion may require. In these ledges, as well as in the intervals between them, a number of holes are to be drilled for the reception of a variety, of pegs of different forms, intended to indicate the various kinds of notes in music ; such as semibreves, minims, crotchets ; together with the rests, flats, sharps, bars, &c.
In a contrivance of Mr Cheese for the same pur pose, and which we have seen actually introduced into some asylums of the blind, a stuffed cushion is sub stituted for the board of Tansure, upon which strings are sewed to represent the musical staff, and the pegs intended to denote the various musical characters, are fixed upon sharp pointed wires, by which means they may be stuck into any required part of the cushion. What we chiefly object to this contrivance, is the multiplicity of pegs, of awkward and arbitrary forms, which it employs, the ready use of which cannot be taught to the blind without a great deal of trouble. Instead of this, we think it would be better to have the heads of the pegs formed into a resemblance of the notes, rests, bars, shakes, &c. which are actually employed in written music, which are sufficiently simple and intelligible, and far from being too nume rous, as they have a relative value from their position, as well as an absolute one from their form.
In the year 1786, au Essay on the Education ofthe Blind was printed at Paris, under the patronage of the Academy of Sciences. It is the composition of,
Haiiy, and does great honour to the author, on ac count of the comprehensive and liberal views which it exhibited. It contains a detail of a great variety of expedients by which the blind may be successfully in structed in many of the mechanic arts, as well as in music, arithmetic, geography, &c. and may even be taught to read, write, and print. In order to in struct the blind in music, at the institution of which M. Haiiy communicates the details in this work, mu sical characters of every necessary form were cast in metal, and so many in number as to represent upon paper, by elevations on its surface, all the possible varieties that occur. In teaching geography, which was the department of M. \Veissenbourg and Mad. Paradis, the circumference of countries was marked out by a tenacious and viscid matter, and the different parts of the maps was covered with a kind of sand, mixed with glass in various modes ; the order of the towns being distinguished by grains of glass of a greater or less size ; or, according to the plan of M. Haiiy, the limits of the maps, for the use of the blind; were marked by a small rounded iron wire ; and by some difference, either in the form or size of every part of a map, the pupils were assisted in distinguish ing one part from another.
The manner in which the blind are taught to write and print, is as followi: The pupil, by repeated ex: periments, having familiarised himself to the forms of the letters as drawn in relief, both in their direct and inverted position, gradually learns to impress them upon strong paper, a little moistened, with the point of a blunt iron pen or stylus, which marks without piercing the paper. By this means the letters become perceptible to the touch, on the one side sunk, and on the other in relievo ; and thus the blind may be ena bled to form and decipher, not only the characters required in common language, but also mathematical diagrams, geographical plans, and all the characters employed in arithmetic, music, &c. In printing, the blind compositor has a box for every letter, on the outside of which is marked in relief, the peculiar cha.: racter belonging to each. By this means lie is enabled readily to choose and arrange his types, and when they are set, he makes use of a strong paper, slightly mois tened, like that employed in writing, in order to ren der it more easily susceptible of impressions. Having laid this upon his types, by the operation of the press, or the strokes of a small hammer, he raises an impres sion upon the paper, which, when dry, is sufficiently obvious to the touch, to enable the blind to read by their fingers, and is so durable as to be by no means easily effaced. This method of printing, it is evident, is also legible by the eye-sight ; and it has one advan tage over that in common use, that the types are set, not in the reverse, but in the direct order, so that the characters may appear in relievo, in the same or der, on the opposite side of the paper. Dr Black-. lock mentions, that he was in possession of a copy of M. Haiiy's Essay, which was printed in the manner now described, and also bound by the blind pupils of the Parisian institution, with great neatness. An English translation of the Essay is annexed to the edition of that gentleman's poems, printed at Edin: burgh in 4to, in 1793.
See .Journal des Scavans, Nov. 19th 1685, which contains James Bernoulli's method of teaching ma thematics to the blind. (at) ••