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an experiment in the Dialogues devised for the purposeof forming one. With regard to the pump, he certainlywould seem to have still held the theory of suction;which is not only a very extraordinary circumstance initself, but the more so because he describes an experi-ment by which he attempted to measure the weight ofair as compared with water.

In another part of the Dialogueswe have some curiousanticipations of the time in which light is transmitted;an account of the vibrations of musical strings, and thecoincidence of their pulsations as occasioning harmony ;with a description of the original experiment, since somuch enlarged upon, of the regular figures assumed bysand strewed on a plate made to vibrate. These subjects,together with that of the strength of beams, comprisethe principal materials of these Dialogues.

After the completion of the “ Dialogues on Motion,”Galileo turned his thoughts again to the method of deter-mining the longitude by the eclipses of Jupiter ’s satellites,and became involved in a discussion of that and otherschemes. Morin, a French philosopher, had proposed,about 1636, a plan, which is, in fact, the same as themethod of lunar distances. Galileo raised against itwhat were, indeed, insuperable objections at that period ;the practical impossibility of executing it with the neces-sary exactness, both from want of tables and instru-mental means. Galileo naturally preferred his ownmethod, the practical difficulties of which do not seemto have struck him.

The application of the pendulum to clocks has beena subject of question, as to the priority of invention, be-tween Galileo and Huyghens . We shall here only observe,that Galileo never claimed it; and, upon the whole, theredoes not appear to us any ground for depriving Huyghens of the credit of it.*

Galileo was now suffering from the increasing infirm-ities of age, as well as several severe attacks of illness:yet, such was the inveterate rancour of his persecutors,

* The evidence is discussed in Drinkwater’s Life of Galileo, p. 98.

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