570 PHILOSOPHICAL TRANSACTIONS. [aNNO I67I. 



Dartmoor there are some considerable loads, which run north and south : these 

 underlie towards the east. 



Four or five loads may run parallel to each other in the same hill, and yet 

 (which is rare) meet all together in one hatch, as it were in a knot, (which 

 well tins the place ;) and so separate again, and keep their former distances. 

 Such a knot has been observed, and wrought on Hingston, a know^n mineral 

 down or common in Cornwall. 



The master loads may generally be from three to seven feet broad, seldom 

 more ; unless at certain places, and where several loads may chance to make a 

 knot, or send forth strings or veins ; neither retain they their usual breadth in 

 all parts : for they may be six feet at one place, scarce two at another ; nay 

 sometimes scarce half an inch over ; but that is to be understood of strings and 

 the narrowest places of the concomitant ones. 



The load is usually in a hard (i. e. in a rocky or shelfy) country, made up of 

 metal, spars, and other weeds, and as it w^ere all along a continued rock ; but 

 has many veins and joints, as we speak ; but in some softer countries the tin 

 may lie in a softer consistence, as that of clay in a manner petrified, whereby 

 it may rationally be expected, that they make more speed and show in their 

 drifts, and the same number of beelemen employ more shovelmen. 



Concerning water, we have these observables; that in most places we meet 

 with it at some feet deep from the loady surface, in others not at many fathoms 

 deep. It runs commonly through the heart of the load, not in a direct con- 

 tinued channel, but windingly in and out, insensibly through the veins and 

 joints of the load. 



When we are come at any depth, and find the water begin to annoy us, as 

 it quickly will if any be in the work, we descend to the bottom of the hill, 

 where we have that conveniency, and at the lowest place begin as little a drift . 

 as the conveniency of working or driving will permit (scarce half so large as 

 that of the load) on a level, till we come up to our work. And here the use 

 of the dial is needful, which we term plumming and dialling, (either to know 

 the exact place of the tin work, where to bring our adit ; or where to sink to 

 bring down our air shaft even with the desired place, perpendicularly ; or to 

 know which way our load inclines, when any flexures happen ;) which is to be 

 performed in this manner, viz. 



A skilful person, with an assistant, pen, ink, paper, compass, and long line, 

 after his guess of the place above ground, descends into the adit or work, 

 and there fastens one end of the line to a fixed thing ; and then lets the in- 

 cited needle rest, exactly observing with his pen at what point it stands ; then 

 he goes farther in, the line still fastened, and at the next flexure in the adit 



