1818.] Charles Augustin Coulomb. 85 



Coulomb has been very little employed in this country, and even 

 in France its use appears to have been principally confined to 

 the author himself, so that its value still rests, in a great measure, 

 upon his authority.* 



Among- the other objects to which Coulomb directed his 

 attention, we must not omit to mention a memoir which was 

 published by the Academy in the year 1781 on wind-mills, in 

 which the author made a great number of experiments on the 

 mills near Lisle, particularly directing his attention to the form 

 of the sails, and the quantity of effect which they were able to 

 produce by a given force of the wind. A very curious and elabo- 

 rate paper of Coulomb was published in the Memoirs of the Insti- 

 tute for the year 1798, detailing numerous experiments on the 

 quantity of power which a man can exert in the course of a 

 day, and on the best method of employing his strength. The 

 author inquires what weight can be best borne during a certain 

 number of hours, how many loads, and of what size, can be 

 carried along a horizontal surface ; and how many by the same 

 person mounting up steps : he afterwards examines the compa- 

 rative force employed in performing many of the common opera- 

 tions of labourers, such as pulling a rope, turning a winch, &c. 

 and endeavours to form accurate estimates on all these points. 

 We think it doubtfid whether all the calculations and deduc- 

 tions contained in this paper, although derived from experiments, 

 which were doubtless made with much care and diligence, are 

 applicable to any useful purposes ; so many circumstances, 

 besides those of a mere mechanical nature, are concerned ; and 



* Coulomb published, in the whole, seven memoirs on electricity, which are con- 

 tained in ihe Memoirs of the Academy for the years 1785, 1786, 1787, 1788, and 

 1789. The following may be regarded as among the most important of the pro- 

 positions which compose his hypothesis of electricity : 



J. There exist two electric fluids, one vitreous, and the other resinous. 



2. The particles of each of these fluids repel each other. 



3. The particles of one of ther,e fluids attract the particles of the other fluid. 



4. These attractions and repulsions are in the inverse ratio of the square of the 

 distance. 



5. The electric fluid does not diffuse itself through different bodies in conse- 

 quence of a chemical affinity, but it is distributed among them when placed in 

 contact, according to their figure or position, solely by its repulsive force. 



6. In conductors, the electric fluid diffuses itself entirely along the surface, 

 without penetrating into the interior. 



7. In electrics, the fluid penetrates into the interior of the body. 



•8. The electric force is not produced by impulse, nor by the action of any ex- 

 traneous impulsive fluid. 



9. The electric fluid does not form active atmospheres around bodies, by the 

 particles of which ihe phenomena of attraction and repulsion are produced, but 

 they depend upon the action of the fluid in the body itself. 



10. When electricity is excited by friction, or by any other means, the two 

 bodies acquire different kinds of electricity, the one vitreous, and the other 

 resinous. 



Coulomb supposed the cause of magnetism to be very analogous to that of 

 electricity; that there were two magnetic fluids; that their particles repel each 

 other; that the particles of one fluid attract the particles of the other | that they 

 act in the inverse ratio of the squares of the distances ; but that the fluid u lodged 

 entirely in the interior of the body. 



