orm of the Hon. Robert Boyle's
hydrometer, which he described in a paper in the "Philosophical
Transactions" for June, 1675, under the title of a "New Essay
instrument." In this paper the author refers to a glass instrument
exhibited many years before by himself, "consisting of a bubble
furnished with a long and slender stem, which was to be put into
several liquors to compare and estimate their specific gravity."
Boyle describes this glass bubble in a paper in "Philosophical
Transactions," vol. iv., No. 50, p. 1001, 1669, entitled, "The
Weights of Water in Water with ordinary Balances and Weights."]

This done, and having spent 6d. in ale in the coach, at the door of the
Bull Inn, with the innocent master of the house, a Yorkshireman, for his
letting us go through his house, we away to Hercules Pillars, and there
eat a bit of meat: and so, with all speed, back to the Duke of York's
house, where mighty full again; but we come time enough to have a good
place in the pit, and did hear this new play again, where, though I
better understood it than before, yet my sense of it and pleasure was
just the same as yesterday, and no more, nor any body else's about us.
So took our coach and home, having now little pleasure to look about
me to see the fine faces, for fear of displeasing my wife, whom I take
great comfort now, more than ever, in pleasing; and it is a real joy to
me. So home, and to my Office, where spent an hour or two; and so home
to my wife, to supper and talk, and so to bed.

10th. Up, and to the Office, where busy all the morning: Middleton not
there, so no words or looks of him. At noon, home to dinner; and so to
the Office, and there all the afternoon busy; and at night W. Hewer home
with me; and we think we have got matter enough to make Middleton appear
a coxcomb. But it troubled me to have Sir W. Warren meet me at night,
going out of the Office home, and tell me that Middleton do intend to
complain to the Duke of York: but, upon consideration of the business, I
did go to bed, satisfied that it was best for me that he should; and so
my trouble was over, and to bed, and slept well.

11th. Up, and with W. Hewer by water to Somerset House; and there I to
my Lord Brouncker, before he went forth to the Duke of York, and there
told him my confidence that I should make Middleton appear a fool, and
that it was, I thought, best for me to complain of the wrong he hath
don