Vthraiion Nodes ofMuJlcal Strings. 347 



tiling in this refpcA is more ftriking than what is ohferved 

 by Columella in regard to the changes of climate. " I find," 

 fays he, " that it is the opinion of many refpe6iable authors 

 that the quality and (late of the atmofphere become changed 

 in the courfe of a long feries of ages : for Saferna, in that 

 work which he has left on agriculture, infers that the ftatc 

 of the atmofphere is changed, becaufe certain dillri^ls, which 

 formerly were incapable of producing vines or olives on ac- 

 count of the continual feverity of the winter, now yield abun- 

 dant vintages and plenty of oil by the climate having be- 

 come milder and warmer*." But it is now time that I 

 fliould proceed to an inquiry into the caufes that produce 

 thefe changes, the effefts of which I flatter myfe)f I (hall be 



able to prove. 



[To be concluded in next Number.] 



II. Ohfervations on the Vibration Nodes of Mufical Stmigs. 

 By J. G, VpiGT of Halle \. 



JtliXPER. I. Divide AB, the firing of a monochord^ into 



any number of equal parts, for example four, by the points 



CDE, and place a moveable bridge at E ; put on the points 



C, D of the firing, and any others at 



pleafure, light bodies, fuch as fmall bits 



■R ofp^pefj and draw a violin bow, rubbed 



'■ * * * ' with rofm, over the partEA; you will 



hear the tone correfponding to the part 



EA, which is to the tone of the whole firing AB as 4 : i j 



^nd all the bits of paper,, except thofe lying on the points 



• Mukos enim memorabiles audtores comperi perfuafuin habere, lorige 



jEvi iltu (iiialiratem cocli ftatumque mmari . Nam (SaftrnaJ 



CO libro qiieiii dt agricultora i'criptum reliquit, mutatum cocli ftatiim fie 

 coUigit, quod, quae rcgioncs antea propter hiemis afliJuam viokntiam nul- 

 lam ftirpem vitis aut olerE dcpofitam cnftodire potucrinr, nunc mitigato 

 jam et jntcpefcentc priftino frit^ore largiliimis olivitatibu:, liberique vindc- 

 f;iiis cxubtrent. De Re Rujlica, Lib. i. cap, i. 



t I'rtim Grcn's Journal UiT Pbxfiky Vol. II. part 3. 



J C and 



