[147] Galileo also reasons in the same way on the equality of the solids standing on the cutting plane, but one is sufficient for our present purpose. [148] Gli altissimi e ultimi termini. [149] Le ultime reliquie e vestigie lasciate da grandezze eguali. [150] Punctum fluere, et lineam esse fluxum puncti. Tract. Syllept. Romæ, 1633. [151] "Treatise of the Nature of Bodies. London, 1665." [152] This beautiful experiment is more easily tried by drawing the bow of a violin across the edge of glass strewed with fine dry sand. Those who wish to see more on the subject may consult Chladni's 'Acoustique.' CHAPTER XVIII. _Correspondence on Longitudes.—Pendulum Clock._ IN the spring of 1636, having finished his Dialogues on Motion, Galileo resumed the plan of determining the longitude by means of Jupiter's satellites. Perhaps he suspected something of the private intrigue which thwarted his former expectations from the Spanish government, and this may have induced him on the present occasion to negotiate the matter without applying for Ferdinand's assistance and recommendation. Accordingly he addressed himself to Lorenz Real, who had been Governor General of the Dutch possessions in India, freely and unconditionally offering the use of his theory to the States General of Holland. Not long before, his opinion had been requested by the commissioners appointed at Paris to examine and report on the practicability of another method proposed by Morin,[153] which consisted in observing the distance of the moon from a known star. Morin was a French philosopher, principally known as an astrologer and zealous Anti-Copernican; but his name deserves to be recorded as undoubtedly one of the first to recommend a method, which, under the name of a Lunar distance, is now in universal practice.