PREFACE. 



o 



N the Completion of this fourth Volume I have the 

 Pleasure to give the Names of the Authors and List of En- 

 gravings. 



The Authors of original Papers are John Gough, Esq. ; 

 N. N. ; J. Fletcher, Esq. ; Ez. Walker, Esq. ; J. Harriott, 

 Esq.; Mr. W. Wilson; Dr. Priestley, F. R. S. &c. 5 Tho- 

 mas Young, M. D. F. R. S. &c; Mr. Benj. Hooke; W. N. j 

 John Bostock, M. D.; G. C, ; R. B.; The Rev. Wm, 

 Gregor ; Mr. Wm. Henry ; Z, ; II; and Lawson Huddle- 

 ston, Esq. — Of foreign Works, G. Dalarive ; Rochon ; 

 Guiton ; Cadet ; Gall ; Bojames ; Klaproth ; Jumilhac ; 

 Saint Victor; J. B. Berard; L. Reynier; Proust; and 

 Fourcroy. — And of English Memoirs abridged or extracted, 

 R. Chenevix, Esq. F. R. S. ; H. Davy, Esq,; S. Tennant, 

 Esq. F. R. S. ; Mr. J. Dalton; W. H. Wollaston, M. D. 

 F. R. S. ; W. Herschel, L. L. D. F. R, S. ; R. Kirwan, 

 L. L. D. F. R. S. ; and M. des Lozieres. 



Of the Engravings the Subjects are, 1. A new sliding 

 Stop for Air-Pumps and other Uses. 2. A simple and se- 

 cure Metallic Joint for Tubes. 3. Mr. Harriott's Syphon 

 Engine for raising and lowering Weights. 4. New Method 

 of measuring the Action of Bodies in refracting Light, 

 whether they be transparent or opake ; by Dr. Wollafton. 

 5. Mr. Hooke's Blow Pipe by Alcohol. 6. The Harmonic 

 Sliders of Dr.Young. 7, A strong and flexible Joint for Tubes. 



8. Dr, 



