AERIAL SURVEYS

Otago Daily Times, Issue 21390, 18 July 1931, Page 14

AERIAL SURVEYS

SECRETS OF THE PAST REVEALED EGYPT’S WATER SUPPLY. (From Our Own Correspondent.) LONDON, June 4. Secrets of antiquity that have remained hidden for centuries are to-day being brought again to the knowledge of men by the aeroplane. In Britain, the Middle East, and other historical regions throughout the Empire the airborne camera is revealing details of tow-ns, settlements and works of olden times that are assisting archaeologists mightily in their reconstructions of the world as it was 15, 20 or more centuries ago. No aspect of aviation is more picturesque. The aeroplane, essentially a twentieth century invention, is frequently the most efficient means available of looking back into the past. Even to the naked eye details of ancient embankments or earthworks, completely invisible on the ground, sometimes become astonishingly perceptible from the air. The earth may have been turned over countless times by the plough, but from above the ancient outlines can still be glimpsed. The supersensitive eye of the camera reveals much more, and photographs secured are often found to show down to the smaller details the ground plan of a settlement lost to human ken more than a thousand years ago.

Much work was done recently in Britain along the line of Hadrian’s Wall, constructed during the Roman occupation nearly two thousand years ago to keep back the “ barbarians ” living north of the Tweed. Royal Air Force pilots flew along the line of the wall and took a series of photographs as part of the regular service training of their unit. The results were surprising, and antiquaries received them with delight. Four camps, previously unknown, were discovered; parts of the wall and the accompanying earthen rampart were shown in much greater detail than the most painstaking ground survey had revealed, and the big settlement of housesteads, which sprang up outside the Roman camp of Borcovicus, was outlined in such detail that antiquaries may reasonably claim that the plan of it is as well known to-day as it was to the settlement’s inhabitants. Points in dispute, such as the precise location of the earthen rampart at one of the chain of forts along the wall, were settled finally by the air photographs. Now the archreologists are suggesting to the Air Ministry that other sections of the wall should be carefully surveyed. MAPPING THE UPPER NILE.

In Libya, Lady Bailey spent a fortnight early this year taking aerial pictures of ground works which mark the sites of towns and burying places built long before the Christian era. Farther south, in the Sudan, more immediately practical survey was recently concluded of the Upper Nile swamps. There experts of the Physical and Irrigation Departments of the Egyptian Government studied from the air the country fed by the Bahr el Ghazal, a tributary of the Nile which may play an important part in the better utilisation of the Egyptian water supply. The scheme under consideration is designed, to lead water from the White Nile so as to avoid the losses caused by evaporation and by soakage into the surrounding country inevitably linked with passage of the water through the swamp lands, as at present. The Irrigation Department has to decide whether to build a canal through or around the swamp lands and aerial survey was selected to answer the question. This important air photographic work was allotted to the Air Survey Company, and two Fairey biplanes did the job in a few months. In the extreme south of the territory photographed, around Lake Albert, the land is hilly, rocky and covered with scrub. A forced landing there would have been dangerous, but aircraft.and engines worked perfectly and at no time was tlTerc cause for anxiety. Now maps are being prepared of the entire region and, whatever may be the official decision, to the credit of the aeroplane will remain an essential preliminary stage in work that should result in vastly increased supply of water to the cultivated lands of the Nile basin.