e Tall ef ER, 1693 pPkob. v. äThree Numberi being given, fo End 4 fourth Proportienal.

1 Golden Rule the moſt uſeful of all others may be wrought ſe-

veral ways, as it appears by this Example:

Arz ante 24: fo 4 fo 4 fourth namber. 5

The ordinary way in Arichmetick is by Multiplication and Diviſion. 1.For firſt chey multiply che ſecond into the third, and then divide the Tactus 2Product by the firſt Number given. As here, multiplying 24 by 4, the 5 3 divi-Product is 96, then dividing 96 by 22, the Quotient will be 8, the fourth enumber here required. R.According to this way we add the Logarithms of the ſecond and third,and ſubtract the Logarithms of che firſt, ſo that which remaineth ſhall bethe Logarithm of the fourth Number required.

Thus che Logarithm of che firſt Number 13 is 1.579 18125he Logarithm of the ſecond 24 1. 38021124The Logarithm of the third e o. 6020599The Sum of che ſecond and third Logarithm 1.98227123Subtract che firſt, and there remaineth 90338998

And chisis the Logarithm of 8, the fourth Proportional. 175

A ſecond way in Arithmetick is by Diviſion and Multiplication. For Quuorie 155

Vhere the ſecond Number is greater than the firſt, they may divide the 2 per 1 di!

ſecond by the firſt, and then multiply che third by the Quotient. As viſ mul

here, dividing 24 by 12, the Quotient is 2: then multiplying 4 by 2, kiplicatus

the Product will be 8. g in textiũ,

According to this way we take the Logarithm of the firſt out of the Lo-garithm of the ſecond, and then add the difference to the Logarithm of thechird. So che Sum of this Additien ſhall be the Logarithm of the fourth

required.

Thus the Logarithm of the firſt Number 12 is 1.079 18125The Logarithm of the ſecond 24 5 1.38021124The Difference between the increaſing 5 301029993 5 5

Added to che Logarithm of f 4 o. o 59Gives the Logarichm of 8. o. good8 8 b 15 A