rOL. Xir.] PHILOSOPHICAL TRANSACTIONS. 37^ 



46, some of which were forgotten in the former edition, some were newly found 

 out by him. Besides many useful observations. 



III. Aero Chalinos; or, A Register for the Air, &c. By Nathan. Henshaw, 

 M.D. Fellow of the Royal Society. Lond. 1677, in 12mo. 



This tract consists of 5 chapters, of which the first treats of fermentation; 

 the second of chyl ifi cation ; the third of respiration; the fourth of sanguifica- 

 tion; and the fifth of the salubrity of frequently changing the air; with a 

 discovery of a new method of doing it without removing from one place to an- 

 other by means of an air-chamber fitted to that purpose. 



IV. A Philosophical Essay of Music. Lond. 1677, in 4to. 



This author's design being to explain the nature of music, he begins to in- 

 quire into the cause of sound; in order to which, he considers some of the 

 chief phsenomena of sound. According to him, sound may be caused by the 

 trembling of solid bodies, without the presence of gross air, and also by the 

 restitution of gross air, when it has been divided with any violence. Having 

 laid down this hypothesis, and left his reader to apply it to the phaenomena, he 

 proceeds to the discourse of music itself, and makes it a considerable part of his 

 business to show, how this action that causes sound is performed by the several 

 instruments of music; having taught his reader first, what a tone is, and that 

 the tones useful in music are those within the scale, in which they are placed as 

 they have relation to each other. Secondly, wherein consists that relation of 

 tones and the union of mixed sounds. Which done, he explains, how tones 

 are produced, and what assistances are given to the sound by instruments. 

 Where he teaches, that wherever a body stands on a spring that vibrates in equal 

 terms, such a body put into motion will produce a tone, which will be more 

 grave or acute, according to the velocity of the returns ; wherefore strings vi- 

 brating have a tone according to the thickness and tension of them; and bells 

 that vibrate by cross ovals, produce notes according to their size or the thick- 

 ness of their sides. 



But finding it more difHcult to show how tones are made by a pipe, where 

 there are no visible vibrations ; he considers the frame of a pipe, and the mo- 

 tion of the air in it, and thereby attempts to find the cause of the tone of a 

 pipe, and the pulse that gives the sound, explaining how tones are made in 

 violins, harpsichords, and dulcimers. 



To this he subjoins an ingenious discourse on the varying and breaking of 

 tones, endeavouring to explain how it is caused, both in strings and pipes, 

 where occur divers pertinent observations concerning the motion of pendulums, 

 the trumpet marine, and the true trumpet, as also the sackbut. Where he 

 takes notice of the advice of Vitruvius in his architecture, that in the structure 



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