100 PHILOSOPHICAL TKANS ACTIONb. [aNNO 17'25. 



Some Experiments conceriiing the Cohesion of Lead. By the same. 

 N°389, p. 345. 



Dr. D. took the leaden balls a and b, fig. 1, pi. 2, the first weighing 1 lb. 

 and the other 1 lb. ; and having from each of them cut off a segment of about 

 -^ inch in diameter, he pressed them together by his hand, with a little twist, 

 to bring the flat parts to touch closer. The balls stuck so fast, that when the 

 hand h, by means of a string, sustained the upper ball a, the lower one B, 

 was sustained by the contact at c, though loaded with the scale s, and weights 

 E, which amounted to l6 lb. A little more weight added separated them, and, 

 on viewing the touching surfaces, it appeared that they did not exceed a circle 

 of -rV inch diameter; but this surface can hardly be measured exactly, on ac- 

 count of its irregularity. The experiment was repeated several times, and the 

 cohesion of the balls was different every time. 



At another time he made the experiment another way, as follows: On the 

 upper pin or bar of the wooden frame odiH, Dr. D. suspended the steel-yard 

 EF, whose hook held up a leaden ball a, of 1 inches in diameter, having a hole 

 through it, at a, to receive a string; the lower ball b equal to, and prepared 

 in the same manner as the first, received the pin oo through its string, so that 

 G, the weight of the steel-yard, was made use of to separate the balls, which 

 happened when it was applied at the number 20, in the first experiment; but 

 in the three following experiments, the balls were not separated till the weight 

 was removed to the numbers 25, 37, and 45, expressing pounds on the 

 steel-yard. 



Lastly, the balls being applied together as before, always cleaning the surface 

 of contact with a knife, and never making a contact sensibly greater than as 

 mentioned before ; the weight g removed quite to the end f, where it weighed 

 47 lb. was not able to separate the balls, so that he was obliged to make use of 

 another steel-yard. He made several other trials, but could not again bring the 

 force of the contact to be equal to 47 lb. How much greater than 47 lb. the 

 force of the contact was in the 5th experiment, he could not determine, by rea- 

 son of an accident; but the surface was much as before. 



An uncommon Ncevus Maternus, or Mole. By Dr. Sleigerlahl, Physician to his 

 Majesty, and F. R. S. N° 389, P- 347- 



Jeremias Rudolph von Walthausen, a captain of the garrison at Danneberg, 

 near Lunebourg, was born Oct. 24, l680, with a very singular mole on his 

 right arm, shoulder, and hind part of his side, not unlike the branch of a 



