2 Observations on T5r. Arbuthnot’j

only loaded with useless Fractions, but are not so near theTruth as might be wish’d. The wrong Principles, those Imean which he had from Mr. Greaves , are as follow:

i. That the Roman Ounce is the same with the EnglijhAvoirdupois

'2. That the Englijh Fenny weighs eight Grains.

Mr. Greaves has been follow'd in the first of these Princi-ples, not only by Dr. Arbuthnot , but by Bishop Hooper andMr. Smith ; tho’ I believe it will be easy enough to prove itwrong. In order to this, let us first find the Value of theAvoirdupois Ounce; then that o£ the Roman in GrainsTroy.

By an Experiment in Warts s Young Mathematician s Guide ,p. 32, it appears, that a Pound Avoirdupois weighs 14 oz.11 pw. 15 \ gr. or 6999.5 Grains Troy.

He calls this Experiment a nice one, and I have Reason tobelieve it so, for I made the same myself, and find but atrifle os a Difference.

I fancy Mr. Greaves made the same Experiment, by weigh-ing a Standard Avoirdupois Pound with Troy Weights ; andwas the first who determin’d the Proportion of the Avoirdu-pois Pound to the Troy Pound to be as 175 to 144, and con-sequently the Avoirdupois Ounce to be 43 7 T Grains Troy,which differs very little from the Avoirdupois Ounce fetch’dout by Mr. Ward\ Pound of 6999.5 ; for if 6999.5 bedivided by 16, the Number of Ounces in an AvoirdupoisPound, it will give

The Avoirdupois Ounce 437.468, &c. Grains Troy,which falls short of the foremention’d Avoirdupois Ounce437.5 by only 0.03 2 of a Grain. The foremention’d Pro-portion also is used by Bishop Hooper, but whence he had itwe are not told. Vide Arbuthnot, p. 283.

As for Dr. Arbuthnot , in order to find the Avoirdupois

Ounce, which he will have to be the Roman , thcff without

any