$60 LECTDRE XXX. 



experiments to be capable of affording determinations of all questions which 

 are of very frequent occurrence in practice. AnappHcation was made to Mac- 

 laurin, and at the same time to Desaguhers, a man of considerable eminence 

 in the mechanical sciences, respecting the quantity of water that might be 

 brought, by a train of pipes of certain dimensions, to the city of Edinburgh. 

 The project was executed with a confidence founded on their opinions, but 

 the quantity actually obtained was only about one sixth of Desaguliers's cal- 

 culation, and one eleventh of Maclaurin's. At a still later period, the 

 French Academicians were consulted respecting a great undertaking of a 

 similar nature; and their report was such as to dissuade the projectors from 

 making the attempt, which was consequently at the point of being abandoned, 

 till a celebrated practical architect insisted, from a rough estimation, deduced 

 from his general experience, that more than double the quantity assigned 

 by the Academicians might be obtained; and the event justified his 

 assertion. 



The experiments and calculations of Robins, respecting the resistance of 

 the air, and the operation of gunpowder, deserve to be mentioned with com- 

 mendation on account of their practical utility ; but he appears to have been 

 less successful in his theoretical mvestigations than Daniel Bernoulli had 

 been a few years before. 



Dalembert attempted, in his treatise on the motions of fluids, which was 

 published in 1744, to substitute, for the suppositions of John Bernoulli, a 

 more general law, relating to all changes produced in the motions of a system 

 of bodies, by their mutual actions on each other ; but his calculations are 

 more intricate, and less easily understood, than some others, which are 

 capable of an application equally extensive. 'The late Professor Kaestner of 

 Gottingen has defended Bernoulli against Dalembert's objections with some 

 success, and has in many instances facilitated and extended Bernoulli's 

 theory ; but there is often a singular mixture of acuteness and prolixity in 

 this author's works. By the side of an intricate and difficult fluxional calcu- 

 lation, he inserts along string of logarithms for performing a simple multi- 

 plication; and in a work which comprehends the whole range of the mathe- 

 matical sciences, he does not venture to determine the square root of 10 with- 

 out quoting an authority. 



