“Signaling by moonlight with the heliograph has been practiced during the last two years on service, and it is hoped that the results will soon be published. I have tried it on two different occasions; first in the Jowaki campaign between General Ross’s standing camp and the Sargasha Ridge, and subsequently between Jutogh and Subathu, distant 12 miles. The signals were intelligible in each instance, but the heliographs and telescopes were set up by day and remained in position till the moon rose, otherwise it is doubtful whether the alignment could have been hit off, unless signal fires had been used. At the time communication was established between the Cabul and Kuram Valleys, advantage was taken of a full moon, and a heliograph set on Kuram from the Agam Pass. The light was seen with the naked eye 12 miles off.

https://books.google.com/books?id=40bOAAAAMAAJ&pg=PA485&lpg=PA485&dq=moon