411 Exper'ivients en the Tranfmijfion of Sound. 



vibrations. Then take a folic! body, fuch as a fmall cylinder of wood, of one foot or one- 

 foot and a half in kngth, and one or two lines in diameter. Place it in contail at on« 

 extremity with the watch, and apply the other end to one of tlie numerous parts of the 

 head which propagate found by the touch * ; for example, with the cartilngiiious parts of 

 the ear ; you will hear tlie found much better than if the ear liad not been clofcd, and tha 

 fonorous body had been placed in the air al the fmallcft diftance froin the organ. 



As th: found was not perceptible at the dillance cf two lines in the firft difpofition, and 

 was very ftrongiy perceived in the fecond ; it is evident that the fmall cylinder propagated 

 found better than almofpheric air. 



When we re(!e£l on this experiment, and the refult it affords, we m<ny, without diffi- 

 culty, perceive, i]ut, in order to afcertain the refpedive force of the propagation of found 

 through folid bodies, nothing more is required to be done than to procure fubllances o£ 

 different natures, to give them the fame form, and fubje£t them to an experiment of this 

 kind. In this manner I made the follovi-ing experiments : 



Experiment 11. I procured fmall cylinders of the dry wood of fir, oak, box, cherry-tree, 

 chefnut-tree, and logwood, each one lii^e in diameter, and one foot iu length. The ears, 

 being then clofcd, I placed them fuccefTivcly in conta£t with the watch, and at the f.;m<i 

 time with the cartilaginous part of the ear, as in the preceding experiment. 



The different cylinders trnnfmitted the found very well ; but its tone ffeemed to szrj 

 vhenever a new cylinder was ufed, and the intenfity appeared to be never exactly the 

 fame. We had no means of afcertaining the difference of the tone (timbre), but the in- 

 tenfity appeared in the following ordtr, beginning with thofe cylinders whicli appeared 

 to propagate found with the greateft aftivity : lir, logwood, box, oak, cherry-tree, 

 chefnut. 



Experiment III. I determined t^ ctlend my refearches to the metals, and conftruiletl 

 metallic cylinders fimitar to the former. When fubjcfted to the fame trial, ihey tranf- 

 mitted the found in general rather worfe than the cylinders of wood. 



The nature of the found appeared likewife to differ in the cylinders of wood and thofe 

 of metal. The tone was not exactly the fame in the different metals, and the intenfity 

 followed this order : iron, copper, filver, gold, tin, lead. 



Experiment IF. I hung my watch fuccefiively to (Irings cf filk, of wool, of hemp, o£ 

 flax, hair, and gut, which were nearly of the fame diameter and exaflly of the fame length 

 as the folid cylinders. One extremity of the firing was applied by the hand in contaft with 

 the cartilage of the ear, while the watch refted on the oppofite extremity of the ff ring, which 

 touched no part of the body. The ftrings thus extended propagated the found witli-iefs 



* AliT.oft every pirt cf il.c licad (iropagates founrf when in immediate contaft wiili a fonorous body. This 

 may be cifilj" proved by applying a watch to ihe ftveral parts after having clofed llic er.is. See my DifTcrt. 

 An,-.l. &c. and my Rechcrches fur rOrga:.c de I'Oiiie et la Propr. des Sons, torn. iii. dcs Mem. dc la Soc. R. Hi 

 Medec. ct !c Journal dc Phyfiquc, 1773, tom. ii. P. 



t *»» li'^^re, which docs not, as I apprehend, imply any difference of acutenefs or gravity in found, but 

 Mother rclatioa for which I know no Englilh word but tone. Thus the lone (limire) of the hamboy differs 

 greatly from ih.ir of the flute when both are in unifcn, and fo likewife 00 the dilF.rent tones (loas) of the Time 

 kind of inftiument. It does not appear fiom tlic text, vjlietlier the acutenefs or gravity of ihefc tranfinittcd 

 (bunds did diCCer ffOBi each other. N. 



force 



