Timing Without a Watch
You can time it without a watch by counting in this way:
one-and-two-and-three-and-up to the number of seconds required. One-and
is one second.
When the seconds have been counted, press the bulb again and if the
camera has not moved you should have a good negative. No hard-and-fast
rules can be given for this work because conditions vary; you must
rely some on your judgment and learn by experience. It is said that
overexposure is better than underexposure and can be handled better in
developing the films, so when in doubt it is well to allow a little more
time than you think should be necessary. Curious results sometimes come
from underexposed films. I once had a print in outline, like a drawing,
from a negative made in the Rocky Mountains. It did not look in the
least like a photograph, there were no shadows, but it was a good
illustration of the scene.