ng the Timber, Poles, &c. that are employed to support it? And
how long the Wood will last, without being spoyled with the subterraneous
fumes and waters? and what wood lasts longest? {335}

35. What Air-shaft belongs to the Mine? Whether it be _single_, or more
than One? Of what breadth the Air-shaft is at the Orifice? Whether it be
convenient enough, or not? How neer it is placed to the Groove; and in what
position? And if there be _several_ Air-shafts, what their Distances and
scituation are in reference to the Groove, and to each other? Or how Air is
supplied, if there be no Air-shafts?

36. Whether they meet with any Waters in the Mine? And, if they do, how
copious they are; at what depths they occur; how they are qualified; and
what way they Spring, &c.

37. Whether they are constant or temporary? whether they increase or
diminish notably in Summer or Winter, or at any other time of the year; and
if they do, at what season that is; how long it is wont to last; and the
proportions of Increase and Decrease?

38. What Expedients and Engines are employed to free the Mines from Water?
The materials, the parts, the bigness, the shapes, the coaptation; and, in
short, the whole structure, number, and way of applying the Instruments,
that are made use off to free the Mines from Water?

39. What are the Conditions, Number, &c. of the _Adits_?

40. Whether the Mine be troubled with _Damps_, and of what kind they are?
whether they come often or seldom at any set time, or altogether
irregularly? what Signs fore-run them? what mischief they do? what remedies
are the most successfully imployed against them, aswell in reference to the
Cleering of the Mine, as to the Preservation and Recovery of the Workmen?

41. What Methods the Mine-men use in following the Vein, and tracing their
passages under ground (which they call _Plumming_ and _Dyalling_) according
to the several exigencies? And whether they employ the Instruments, made
with the help of the Load-stone, the same way that is usual; and if not,
wherein they differ in the use of the same Instruments; or what Instruments
they substitute in their place?

42. What ways they take to secure themselves from the uncertainty, incident
to the guidance of _Magnetick_ Needles from the _Iron-Stone_ or Ore, that
they may meet with under ground? {336} (of which yet perhaps there is not
so great danger, as one may imagine; as far as I could find by a Trial, I
purposely made in a Groo