On the general principles of the Resistance of Fluids. 135 



from it, serves to keep this jar in a proper position ; that is in fact 

 concentric with the outer jar. 



In this last mentioned experiment, I employed an air pump upon 

 a new construction, which I have lately contrived, and of which I 

 shall soon publish a description. 



Art. XV. — On the general principles of the Resistance of Fluids, 

 in a notice of the Fifth Article of JVo. XJ^ of the Southern Re- 

 view;* by Lewis R. Gibbes, Columbia, S. C. 



The works selected as the subjects of the review are, " Remarks 

 on Canal Navigation, he. by W. Fairbairn, Lond. 1831," and "A 

 new Theory of the Resistance of Fluids, he. by T. Tredgold, article 

 41st of Phil. Mag. April, 1828." The first portion of the review- 

 is occupied by remarks on the great utility, and, indeed, necessity, of 

 uniting sound theoretical knowledge with practical information. Fair- 

 bairn's work, the reviewer observes, shows the want of this combina- 

 tion, while Tredgold's works, particularly his "Treatise on rail roads 

 and carriages," evince the superiority derived from it. The reviewer 

 next proceeds to state the experiments detailed in Fairbairn's work. 

 The results of these are, that when boats, single or twin, were drawn 

 on a canal with different velocities, from five to thirteen miles an hour. 



* Prof. Silliman — Dear Sir — Ever since the publication of the article, " Re- 

 marks on Canal Navigation and the Resistance of Fluids," in the eighth volume of 

 the Southern Review, (tifth article of No. 13,) i have been expecting, with no little 

 interest, to see or hear of some notice of it, but as yet none has come to my knowl- 

 edge. At this I am somewhat surprised, as from the principles the able writer of itt 

 has demonstrated, it is peculiarly valuable to the science of hydrodynamics, so much 

 cultivated during the last half century by the French and Italians. Perhaps, from 

 the comparatively small extent of circulation enjoyed by that work, the article has 

 been seen by few to whom it would prove interesting, and has therefore met with 

 no attention, especially as theory has lent but little aid to the practical engineer in 

 this branch of science. I am induced, therefore, to give the following short notice 

 of the contents of the article referred to, in the hope that it may meet the eyes of 

 others, who with abilities far beyond mine, will duly appreciate the subject, and do 

 it full justice. I have annexed a few of the simplest results of the important theo- 

 rem furnished by the article, which will illustrate the difference between it and the 

 theorem usually given in books on the subject. If you think the whole worth in- 

 serting in your Journal, by so doing you will oblige your obedient servant, 



Lewis R. Gibbes. 



I Rev. James Wallace, Prof. Math. AstroD. in South Carolina College. 



