Decimalizing English Money.

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applications to other purposes, which might be used with advantage: e.g.

The computation of the time of falling bodies.

The conversion of our weights and measures into French.

Finding the length of circumference and radii, and the area of circles and squares.

Actual measurement of the play ground or a neighbouring field, and elementary land surveying.

The right use of annuity and insurance tables, e.g. the tables at the end of the Post Office Guide will suggest many interesting forms of sums.

The use of logarithmic tables, and the solution of triangles by means of them: their application to the determination of the heights of mountains or spires or the breadth of rivers.

The difference of time between various places whose longitude is given.

The measurement of distances on a map which has a scale of miles attached to it.

The readings of the thermometer and the conversion of Fahrenheit to centigrade.

The statistics of attendance in the school itself, and the method of computing its average attendance.

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One great help to the easy solution of money questions Reduction is the habit of using decimal equivalents, or reducing sums of English of money at sight to decimals of £1. We are at present decimals. far from the adoption of a decimal coinage in England; but we can by anticipation enjoy, in our accounts at least, many of the advantages of a decimal system of money, by the adoption of a simple rule. Let it be observed that two shillings £1, that one shilling £05, that sixpence £025, and that a farthing differs only from Loor by a very small fraction; and it then becomes very

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easy to frame a rule for conversion of ordinary expressions for money into their equivalent decimal expressions.

Thus £17. 16s. 73d.= £17.832, because 16s. =8 florins or £·8; 6d. = £*025, and 7 farthings = £*007.

In like manner £21.367 = £21 +3 florins or £3 +1 shilling or £05 +17 farthings or £017, or in all £21. 75. 41d.

Half an hour's practice in conversion and reconversion in this way renders the process familiar. All questions in which the given sum of money does not extend to lower fractions than 6d. can evidently be solved with perfect accuracy by decimals, and without encumbering the mind with the ordinary reduction at all. Nearly all questions in Interest and many in Practice and Proportion can be wrought much more expeditiously by this than by any other method. Precaution is needed in those questions only in which odd pence and farthings occur and require to be multiplied.

These various applications of arithmetic have different relation to degrees of utility; but their value is not to be measured test of real by inquiring which of them is most likely to be practiutility. cally useful. The true aim in devising exercises in practical arithmetic is to cultivate general power, fertility of resource, and quickness in dealing with numbers; the habit of seeing at once all round a new problem, of understanding its bearings, and applying the best rule for its solution. Power of this kind is available, not only in all businesses alike, but in the intellectual and practical life of those boys and girls who are not likely to go to business. And this general quickness and versatility is just as well promoted, we must remember, by working problems which have an abstract look as by solving those in which the phraseology of the counter or the exchange is most ostentatiously used.

One other department of mathematics which has Practical found its way into schools, resembles Arithmetic in being Geometry. an Art and having useful practical applications, and also in furnishing disciplinal and purely intellectual exercise. Demonstrative Geometry has a value for this latter purpose, which, from the days of Plato and Archimedes, has been very generally recognised; but the claims of merely practical geometry as a useful part of both of primary and of secondary instruction appear to me to deserve more consideration than they generally receive. Every scholar should be taught to use the compass and ruler, and the quadrant and scale of equal parts. He should draw simple geometrical figures, as well as talk about them, and recognise their properties. He should know how to measure angles and lines, and to construct ordinary plane figures. In the best schools of Germany, France, and Switzerland, these simple things are taught to every scholar as matter of course. You may hear a teacher dictate to the class directions one by one as to the construction of a figure. "Draw a line 15 centimètres long, then another line upon it at an angle of 35 degrees, then another line of a given length to the right or left, &c., &c." until the class produces one after another figures which he has pre-determined, and of which the qualities and dimensions are afterwards explained and discussed in the class. The rules for practical geometry are comparatively few and simple; the exercise is interesting, and is a considerable relief from graver employment. It serves to familiarize the scholar with the properties of circles, of triangles, or of parallelograms, and so to make the future scientific study of geometry more intelligible. And for those who may never learn Euclid or even the modern system of demonstrative geometry which seems destined to supersede it,

geometrical drawing will be found to have a value of its own in enabling scholars to judge better of heights and distances, and to know at least the chief properties of plane and solid figures.

Note on the form of Abacus. An ingenious modification of the Abacus, or ball-frame, in use in some of the French schools, possesses some advantages over the square Chinese frame with horizontal bars which is in common use in English schools. It is thus constructed:

A much greater variety of exercises in subtracting and combining numbers can be made by means of this instrument; and the upright lines may be made very useful in explaining the principle of our notation, and the necessity for keeping hundreds, tens and units in columns.

XI. ARITHMETIC AS A SCIENCE.

HAVING Sought to lay down some rules by which a teacher may be guided in making the mere arts of computation and measurement effective parts of education, it becomes necessary to consider more fully the claims of Arithmetic as a science, and the reasons for assigning to it as a disciplinal study, even a higher rank than would be due to its practical usefulness.

We should all be agreed that the main purpose of our Science. intellectual life is the acquirement of truth, and that one of the things we go to school is to learn how to acquire it. The mere accumulation of facts and information does not supply what we want. The difference between a wise man and one who is not wise consists less in the things he knows than in the way in which he knows them. We call arithmetic a science, and science, it may be said, means knowledge. But there is a good deal of knowledge which is not science. Science, properly so called, is organized knowledge, knowledge of things and facts and events in their true relation and co-ordination, their antecedents and consequences,-the recognition of every separate phenomenon in the shifting panorama of life as an illustration of some principle