ated with shellac by heating and rubbing
upon the shellac. As previously noted, the shellac must not be
overheated.

The thread is cut off below the lower slip of paper, and the upper
support being conveniently laid in a horizontal position on another
dead-black surface, the thread is carried to it and laid as designed
against the shellac, which is now cold. When the thread is in place,
a soldering iron is put against the brass wire, and the shellac
gradually melted till it closes over the thread.

Fig. 71.

The iron is then withdrawn and the thread pulled away from the point
for one-twentieth of an inch or less. This ensures that the thread
makes proper contact with the cement, and also that it is free from
kinks; of course, it must leave the cement in the proper direction. A
similar process is next carried out with respect to the lower
attachment, and the ends of the thread are neatly trimmed off.

Both ends of the thread being secured, the next step is to transfer
the upper support to a clip stand, the suspended parts being held by
hand, so that the weight comes on the thread very gradually. In this
way it will be easily seen whether the thread is bent where it enters
the shellac, and should this be the case, a hot iron must be brought
up to the shellac and the error rectified.

When both the support and the suspended parts are brought nearly to
the required bearing, the hot iron is held for a moment close up to
each attachment, the hand being held close below but not touching the
suspended parts, and both attachments are allowed to straighten
themselves out naturally.

These details may appear tiresome, and so they are when written out at
length, but the time occupied in carrying them out is very short, and
quartz threads break easily, unless the pull upon them is accurately
in the direction of their length at all points.

In the event of its being decided to attach the thread by soldering,
the process is rather more expensive in time, but not otherwise more
troublesome.

Fig. 72. Fig. 73.

The thread being cut as before to the proper length, little bits of
aluminium foil are smeared all over with melted shellac and suspended
from the thread replacing the paper slips before described. It is
important that no paraffin should be allowed to touch the thread
anywhere near a point intended to be soldered. The thread is hung up
from a clip stand by one of the bits