THIS contribution to the teaching of arithmetic consists of two charts, each 40 in. by 10 in., which can be mounted, or otherwise adapted to class teaching. Chart i., whole numbers, consists of a series of horizontal lines, divided by dots respectively into ones, twos, threes, &c., twelves. By means of vertical lines the multiples of 2, 3, &c., are shown on the line of ones, which is numbered from 0 to 144. In Chart ii., fractions (vulgar and decimal), the series of horizontal lines are 1 metre in length and 1 cm. apart. These lines are divided by dots into halves, thirds, &c., tenths. There are subdivisions into hundredths (cm.) and thousandths (millim). On Chart i. explanations are given of magnitude, unit, number, multiple, &c.; and on ii., of the multiplication and division of decimals, the expression of a vulgar fraction as a decimal, and several other matters. The charts are well adapted for the purpose of giving a sound grounding in the subject, so far as they go.