I

CHAP. XLIV.

NAPLER'S RODS.

WAS amufing myfelf, this morning,

with a fort of mechanical arithmetic, ftiled Napier's Rods; which is a method of performing questions in multiplication or divifion, as alfo of extracting the Square and Cube Roots, by the help of inftruments, fomewhat like the Sliding Rules, for gauging and measuring of timber, contrived for the purposes of arithmetic, and propofed to be made ufe of for expediting of calculations in numbers.

I shall not encumber this chapter with a defcription of thefe Shifting Tables, F 4

as.

as I do not mean to teach their fervices to the unlearned; but caly design to give my opinion to thofe who happen to be already acquainted with them, that they appear to me to be rather curious, than useful, and may not im properly be defined, a difficult method of doing an eafy thing.

However, thefe Rods would be very ufeful in forwarding Learners in arithmetic; and for this purpose I recommend them strongly. For this fcience is rather too abftracted a ftudy for tender minds; and thefe Lamine might engage the attention of youth, where reafoning would but diftract it. As it has been found by experience that the

Ccnic Sections are fooner taught by the Solids, than by Diagrams.

For children are obferved generally to be fonder of learning to write, because it is a mechanical exercife, than they are of reading, which is an intellectual one. And in this cafe I would have the plates fquared and divided, as ufual, though in reality not neceffary to the operations, but the more to amufe and excite the curiofity of the pupil.

The practice of thefe Tables may be rendered a kind of play, to beginners, to the full as entertaining as any of the childish ones they are taught to divert themselves with. And in truth; I have often thought it very poffible

for

for a good mechanical genius to contrive inftruments or devices of sport, that might be able to carry the great point of the utile dulci with them, and teach the whole circle of arts and fciences, by exercifing the mind, through the amusements of fancy.

There are feveral Tricks, as they are called, on cards, and many other diverfions fit to entertain youth with, that depend on mathematical knowledge and philofophy; and when the effects are pleafing, one is the more inquifitive about the cause.

This may lead them on, by degrees, to more abstruse, though equally pleafant, investigations of fcience, be the reference

ference to what it may. For fuch is the nature of truth, that it charms and captivates the mind, as much in the contemplation of atoms, as of worlds.

These contrivances need be but fimple, for the instruction of children; as a Totum, for instance, marked with the four cardinal points; the fpindle to be called the poles, and its whirling marked out as the circulation of the heavens on their axes. But for more adult years, the artifice should be perfectly ingenious, to rival the higher Occupations of cards, dice, or baggammon; to which the prefent race of mankind dedicate their whole application.

And