7l6 PHILOSOPHICAL TRANSACTIONS. [aNNO I672. 



that a lens be placed in the hole F, or immediately after the prisms, so that its 

 focus be at the image Q or PT. For thereby the perimeter of the image Q, 

 and the straight sides of the image PT, will become much better defined than 

 otherwise. 



Account of a Stone cut out from under the Tongue of a Man. By 

 Mr, Lister. N" 83, p. 4062. 



The man's opinion is, that it was caused by a winter sea voyage, which lasted 

 much longer than he expected, and wherein he suffered an exceeding cold ; and 

 that, not long after his landing, he perceived a nodus or hard lump in the place 

 whence this stone was cut. About eight years passed between its breeding and 

 being taken away. 



As to its growth and the inconveniences thence ensuing; he further says, 

 that upon all fresh cold-taking, he suffered much pain in that part; and yet that 

 cold once being over, the part was no more painful than the rest of his mouth. 

 He adds, that towards the seventh and eigthth year it often caused sudden swel- 

 lings in all the glands about the mouth and throat, upon the first draught of 

 beer at meals, which yet would in a short time fall again. 



Lastly as to the particulars remarkable at the time of its being taken away, 

 he relates ; that it began its work with a sudden vertigo, which vertiginous dis- 

 position continued more or less, from spring till August, in which month, with- 

 out any previous cause, save riding, the place where it was lodged suddenly 

 swelled, and emitted purulent matter at the aperture of the Whartonian duct. 

 That it suddenly stopt its running, (which he cannot attribute to any thing but 

 cold) and swelled with a great inflammation, and very great danger of choaking, 

 causing extreme pain to the party when endeavouring to swallow any thing 

 liquid. 



This extremity lasted five days, in all which time the party had so extreme 

 a salivation that he could not sleep, without wetting all the bed about him ; 

 so as that it was supposed by his visitors that he had made use of some mercu- 

 rial medicine. The first day, the saliva ran thin and transparent almost like 

 water without bubbles. The second day it ran frothy, it tasted salt, (which yet 

 he is apt to think hot rather than really salt, because that day the inflammation 

 was at the height). The third day it roped exceedingly, and a small pin hole 

 broke directly over the place of the stone, and ran with purulent matter as for- 

 merly. The fourth day the saliva ran insipid, sensibly cold in the mouth, and 

 very little frothy ; the coldness confirms me in the opinion, that the former 

 sharp taste was the effect of heat_, and not the immediate quality of a salt hu- 



