Mr. Tredgold on a new Theory of the Resistance of Fluids. .249 



8. Kelloways rock, which appears on the northern edge 

 of the oolitic lulls, but is not seen at the surface 

 in the Vale of Pickering. 

 Dec. 1827. 



XLI. A new Theory of the Resistance of Fluids, compared with 

 the best Experiments, By Mr. Thomas Tredgold, CVw7 

 Engineer; Hon. M. Inst. Civ. En., and of the Liter, and Phil. 

 Society of Newcastle-upon-Tyne.* 



[With an Engraving.] 



1. HPHE following is an account of some inquiries respecting 

 f- the resistance of fluids, which were undertaken to en- 

 able me. to render more effectual assistance to those who con- 

 sult me on subjects where an accurate knowledge of this re- 

 sistance is of importance : a further motive to proceed in the 

 research was the extensive application of which it is susceptible 

 among the wants of a commercial nation. With a like sense of 

 its utility it was long ago remarked by Dubuat, " that to de- 

 termine the resistance which a body in motion experiences 

 in a fluid at rest, is one of the most important problems of 

 general mechanics;" and since that time it has acquired still 

 greater interest, in consequence of the application of a new 

 species of power to propel vessels at sea. 



2. Since I commenced the investigation, the French Aca- 

 demy of Sciences have offered a premium for the best series 

 of experiments on the resistance of fluids* ; and certainly a good 

 series of experiments under a great variation of conditions would 

 be valuable ; but when they are not made for the express pur- 

 pose of determining particular truths, or data, they become of 

 little value in assisting the progress of scientific investigation. 

 The object of an experiment, like that of an equation, is the 

 determination of something unknown; the same principles ap- 

 ply to both cases. The fine discoveries which made chemistry 

 a science, resulted from experiment conducted by the methodi- 

 cal system of the mathematicians, though not in the same tech- 

 nical form. 



I have felt the defects of the miscellaneous system of experi- 

 ment, in attempting to correct and confirm my own inquiries ; 

 but have compared them with the best I am acquainted with. 



3. When a body is moved forward in a fluid, the parts of 

 the fluid before the body must be displaced ; the force required 

 to produce this effect is the measure of the direct resistance. 



* Read to the Lit. and Phil. Society of Newcastle-upon-Tyne ; and com- 

 municated by the Author. 



New Series. Vol. 3. No. 16. April 1828. 2 K 4. The 



