On his left was a window, and above him was the astrodome, used for visual signalling and by the navigator for celestial navigation.
12.
Telephone lines were cut, wireless sets were damaged, power buzzers were useless in the wet ground and the bad light made visual signalling very difficult.
13.
Visual signalling failed in the mist and few runners got through the German standing barrage, which left the situation at the front unclear, until stragglers began to appear.
14.
As time passed, the volume of German small-arms fire sweeping Ovillers Spur cut off communication with the troops in the German defences, even by visual signalling.
15.
The landing force had been out of radio contact since 2 : 00 pm, and the destroyer was unable to raise it with either her radio or visual signalling devices.
16.
One early communication method was for the flier to write a note and drop it to the ground where it could be recovered but various visual signalling methods were also used.
17.
Some 12, 000 servicemen passed through her signal instruction school in Sydney, acquiring skill in Morse code and visual signalling ( flag semaphore and International Code of Signals ).
18.
Due to constant cutting of the telephone lines and bombardment haze making visual signalling impossible, the commander of the 9th Brigade rode forward to assess the situation and ordered the advance to continue towards Jiyus.
19.
He was for several years engaged with Captain Philip Howard Colomb R . N . in developing a system of visual signalling, applicable to naval and military operations, which was adopted by the authorities.
20.
From 1867 to 1869 Bolton was deputy-assistant quartermaster-general and assistant instructor in visual signalling at the School of Military Engineering at Chatham, under Captain Richard Hugh Stotherd, the instructor in telegraphy.
