7 86 THE POPULAR SCIENCE MONTHLY. 



In his " Method for making a History of the Weather," * the attention 

 of observers is especially directed to the following " particulars," as 

 "requisite for the raising of axioms whereby the cause or laws of 

 weather may be found out " : 1. The strength and quarter of the winds. 

 2. The degrees of heat and cold. 3. The degrees of dryness and moist- 

 ure observed with a hygroscope " made with the single beai'd of a 

 wild oat perfectly ripe, set upright and headed with an index." 4. 

 The degrees of pressure of the air. 5. The constitution and face of 

 the sky. 



It is perhaps worth remarking that our present system of meteoro- 

 logical observations corresponds with tolerable accuracy to Bacon's 

 notion of how a " history " of any special branch of physics should be 

 compiled ; with this difference in result, that, instead of arriving at 

 " axioms " and " forms," we have as yet obtained only a set of em- 

 pirical rules which, however practically useful, can scarcely be said to 

 constitute a science. 



"Discoursed with Mr. Hooke," Pepys wrote, August 8, 1G66, "about the 

 nature of sounds, and he did make me understand the nature of musicall sounds 

 made by strings, mighty prettily ; and told rue that having come to a certain 

 number of vibrations proper to make any tone, he is able to tell how many 

 strokes a fly makes with her wings (those flies that hum in their flying) by the 

 note that it answers to in musique, during their flying. That, I suppose, is a little 

 too much refined, but his discourse in general of sound was mighty fine." t 



Notwithstanding Mr. Pepys's skepticism, Hooke was on this occa- 

 sion not " refining " overmuch. He exhibited in 1681 an instrument 

 (with the principle of which he had doubtless long been acquainted) 

 for counting the pulsations of sound, which seems to have been virtu- 

 ally identical with that now known as "Savart's Wheel." He also 

 anticipated Chladni's celebrated experiment by strewing flour on a 

 vibrating glass bell, thus presenting to the eye, as it were, a picture of 

 the configuration of rest and motion on its surface. It was one of his 

 favorite ideas that, by some future discovery, the sense of hearing 

 would be reenforced as prodigiously as the sense of sight had already 

 been by the telescope an intuition singularly realized by the recent 

 invention of the telephone. " It has not yet been thoroughly exam- 

 ined," he wrote in 1664,J "how far Otocousticons maybe improved, 

 nor what other ways there may be of quickening our hearing, or con- 

 veying sound through other bodies than the air." "By very casual 

 trials," he tells us elsewhere, he had made some progress in this direc- 

 tion, and was by no means convinced that they might not be prosecuted 

 so far as to render audible noises made at the distance of the planets ! 

 Although acknowledging that to his own prejudices this seemed "a 

 very extravagant conjecture, . . . yet methinks," he adds, " I should have 



* Published by Sprat, "History of the Royal Society," p. 173. 

 f Pepys's " Diary," vol. iv., p. 43, Bright's edition. % " Micrographia," preface. 



