Both these surveyors, as well as the others, in the first place make use
of the haulage rope. These they measure by means of others made of linden
bark, because the latter do not stretch at all, while the former become very
slack. These cords they stretch on the surveyor's field, the first one to
represent the parts of mountain slopes which descend obliquely. Then the
second cord, which represents the length of the tunnel to be driven to reach
the shaft, they place straight, in such a direction that one end of it can touch
the lower end of the first cord; then they similarly lay the third cord straight,
and in such a direction that its upper end may touch the upper end of
the first cord, and its lower end the other extremity of the second cord, and
thus a triangle is formed. This third cord is measured by the instrument
with the index, to determine its relation to the perpendicular; and the length
of this cord shows the depth of the shaft.
of the haulage rope. These they measure by means of others made of linden
bark, because the latter do not stretch at all, while the former become very
slack. These cords they stretch on the surveyor's field, the first one to
represent the parts of mountain slopes which descend obliquely. Then the
second cord, which represents the length of the tunnel to be driven to reach
the shaft, they place straight, in such a direction that one end of it can touch
the lower end of the first cord; then they similarly lay the third cord straight,
and in such a direction that its upper end may touch the upper end of
the first cord, and its lower end the other extremity of the second cord, and
thus a triangle is formed. This third cord is measured by the instrument
with the index, to determine its relation to the perpendicular; and the length
of this cord shows the depth of the shaft.
Some surveyors, to make their system of measuring the depth of a shaft
more certain, use five stretched cords: the first one descending obliquely;
two, that is to say the second and third, for ascertaining the length of the
tunnel; two for the depth of the shaft; in which way they form a quadrangle
divided into two equal triangles, and this tends to greater accuracy.
more certain, use five stretched cords: the first one descending obliquely;
two, that is to say the second and third, for ascertaining the length of the
tunnel; two for the depth of the shaft; in which way they form a quadrangle
divided into two equal triangles, and this tends to greater accuracy.
STRETCHED CORDS: A—FIRST. B—SECOND. B—THIRD.
C—FOURTH. C—FIFTH.
D—QUADRANGLE.
D—QUADRANGLE.
These systems of measuring the depth of a shaft and the length of a
tunnel, are accurate when the vein and also the shaft or shafts go down to the
tunnel, are accurate when the vein and also the shaft or shafts go down to the