I know of nothing else, in the Book, that requires previous
explanation.

_________________________________________________________________

I think it well to embrace this opportunity, the best I have had, and,
perhaps, the last I ever shall have, of making some return, (as far as
acknowledgement is a return,) for an obligation, of a nature never to
be repaid, by acknowledging publicly, that, to the best and most
affectionate of brothers, I owe the invention of those Charts.

At a very early period of my life, my brother, who, in a most
examplary manner, maintained and educated the family his father left,
made me keep a register of a thermometer, expressing the variations
by lines on a divided scale. He taught me to know, that, whatever can
be expressed in numbers, may be represented by lines. The Chart of
the thermometer was on the same principle with those given here; the
application only is different. The brother to whom I owe this, now
fills the Natural Philosophy Chair in the University of Edinburgh_.

[end of page #xvi]




CONTENTS.

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