VOL. VI.] PHILOSOPHICAL TRANSACTIONS. S65 



may fall close together; and so a right line, joining them, shall be produced 

 with uncertainty; in such case the circle may be conceived to pass through the 

 place of station at S, and any two of the objects, as in fig. 15, through B and 

 C, wherein making the angle DBC equal to the observed angle AS C, and 

 BCD equal to the complement to 180 degrees of both the observed angles in 

 DSB; thereby the point D is determined, through which, and the points C, 

 B, the circle is to be described; and joining DA, produced when necessary, 

 where it intersects the circle, as at S, is the place of station sought. 



This problem may be of good use for the due situation of sands or rocks, 

 that are within sight of three places upon land, whose distances are well known ; 

 or for chorographical uses, &c. Especially now there is a method of observing 

 angles very accurately by the telescope; and it was therefore thought fit to be 

 now published, though it be a competent time since it was delivered in 

 writing. 



Some Observations on the Mines of Cornwall and Devon; describing 

 the Art of Training a Load; the Art and Manner of Digging the 

 Ore; and the Way of Dressing and of Blowing Tin. Communicated 

 by a Person acquainted ivith those Mines. N" 69, p- 2096. 



It is supposed by the miners, that there has been a great concussion of 

 earth in that separation of " the waters from the waters" at the creation, or in 

 Noah's flood, or at both times, whereby the waters moved and removed the 

 then surface of the earth. That before this concussion, the uppermost surface 

 of mineral veins or loads did in most places lie even with the then real, but now 

 imaginary surface of the earth, which is termed by the miners, the shelf, fast 

 country, or ground that was never moved in the flood. 



That in this concussion of waters the surface of the earth, with the upper- 

 most of those mineral veins, were then loosed and torn ofi^, and by the descend- 

 ing of the waters into the valleys, both the earth or grewt, and those mineral 

 stones or fragments, so torn off from their loads, which are constantly termed 

 shoad, were together with and by the force of the waters carried beneath their 

 proper places, and from some hills even to the bottoms of the neighbouring 

 valleys ; and thence by land floods, many miles down the rivers ; in others more 

 or less distant in the sides, according to their declivity and to the impetuosity of 

 the waters. 



Now these three general rules, on which seem to depend the grand reasons 

 of this art, being supposed and premised, we thus proceed to training a load, 

 or tracing a vein of ore. 



