28 ESSAYS AND OBSERVATIONS 



}ike a piece of poliflied filver : but, as it is 

 confidcrably rough and unequal, the under 

 furface becomes rough iikeways ; and fo, by- 

 reflecting 



forcibly brought to tlie fide of the vcfTcl, will fly from it with 

 an accelerated motion. Cafe 4. If, in a fluid which is formed 

 into a convex furface at the fides, a repelling body be im- 

 jnerfed ; as foon as its depreflion begins Kb unite with the la- 

 teral deprefiion oftheflcid, it will move towards the fide 

 with an accelerated motion. In thefe two laft cafes, the 

 fame obfervation holds as with refpea to the firll; and 

 fecond, w'k. that the whole fluid will move with correfpon- 

 dent motions by the force of reaction, if the repelling body 

 be held faft. Cafe 5. If two bodies be immerfed in a fluid, 

 which each of them attraSs ; as foon as their elevations 

 begin to join, they will rufli tosvards one another with equal 

 forces and accelerated motions, and continue to adhere to- 

 gether. Cafe 6. If two bodies be immerfed in a fluid 

 which they repel ; as foon as the two depreflions that fur- 

 round them begin to interfere, they will Iikeways rufli to- 

 gether with an accelerated motion. Cafe 7. If two bodies 

 be immerfed in a fluid, the one of which attrads and the 

 other repels it ; as foon as the depreflion furrounding the one 

 {jegins to join with the elevation of the other, they will mu- 

 tually fly from each other. Lojily, If a body be immerfed 

 in a fluid which it attrafts in one part and repels in another, 

 it will approach to or recede from other bodies and pans of 

 the fluid, differently according to its fituatien, by the rules 

 above laid down. 



The difl"erent figures afcribcd to the furface of the water 

 in thefe feveral cafes are plainly discernible by the fight : 

 if the experiments arc made with candle-light, they are dif- 

 ^inguiflied by the fliadowy or luminous rings which they 



