APPARATUS FOR CONDUCTING SOUND. C9 



out of eleven articles in my TraSl on Phlogijlon ; and befides 

 this, he mould confider what I have advanced on the fame 

 fubject in other publications, efpecially my experiments on the 

 generation of air from water, both by evaporation and by 

 freezing, and thofe on the pile of Volta, and alfo feveral ar- 

 ticles in the Tranfactions of the Philofophical Society at Phi- 

 ladelphia. 



As to the manner in which a controverfy of this kind is 

 conducted, whether it be expreffive of refpecl, or contempt, it 

 will have little weight with a judicious reader. Preferring 

 however a plain and calm difcuffion, 



I am, 



Dear SIR, 

 Your's fincerely, 



J. PRIESTLEY. 



II. 



The Conjiruclion of an Apparatus for conducling Sound and hold- 

 ing Converfations at a Dijlancc. In a Letter from Mr, 

 Ezekiel Walker. 



To Mr. NICHOLSON. 

 SIR, 



QOME of the molt important inventions were at iiril made Several very im. 

 ufe of, either as playthings for children, or in exhibitions to tk>ns we'rTat * 

 amufe the populace. firft confiderei 



Printing, which has contributed more to the improvement S JSS^ 

 of the human mind than any other art, was invented for amufe- 

 ment, and the inftru&ion of children *. But the true value 

 of an invention is not immediately feen, it has to go through a 

 long feries of improvements, before it arrives at a degree of 

 perfection that is important to fociety. 



The loadftone was long known to jugglers, and ufed by Effefts of the 

 them in their exhibitions, before it was applied to the impor- l° adftone ' 

 tant purpofe of navigation : and how far the improvements in 



• Hiftory of Holland by Adrian Young. 



mechanics, 



