Portal de Periódicos da CAPES

Balloon Photography 1

1885; Nature Portfolio; Volume: 32; Issue: 827 Linguagem: Inglês

10.1038/032420a0

1476-4687

Oil Spill Detection and Mitigation

RECENT experiments in photographic aerostation, carried out by M. Gaston Tissandier, with the assistance of M. Ducom, have been attended with very complete and satisfactory results. The photograph reproduced by heliogravure in Figs, i and 2 was taken at an altitude of 605 metres over Paris; others which were taken did not give such perfect results; nevertheless, some of them surpass in distinctness any yet taken by the same method. The ascent took place at Auteuil on June 19, M. Ducom attending specially to the photography, while M. Tissandier looked after the balloon. The photographic apparatus arranged in the car is shown in Fig. 3. The ascent took place at 1.40 p.m. with a south-west wind. Ten minutes after starting a first photograph was taken at 670 metres; soon afterwards another was taken at about the same height, in which a bridge, quay, public office, fifteen cabs, a tramway, and the people in the streets were clearly reproduced. At 605 metres the photograph here reproduced was obtained, but unfortunately heliogravure does not produce an exact fac-simile in the fineness of the details. The smaller plan (No. 2) shows the exact topography of the place. When the photograph itself is examined through a magnifying glass many details are discovered, such as the coils of a rope mooring a boat to the shore, the passers-by, &c. On the photograph, too, the chimneys may be counted forming a number of small black spots on the roofs. A picture of great clearness, but rather greyish, was taken a few minutes later at an altitude of 800 metres above the prison of La Roquette; and another at the moment of leaving Paris at 820 metres. Beyond the city two more photographs were taken at greater altitudes-one at 1000, and one at 1100 metres. Hence in crossing Paris, between 1.40 and 2.12, or in twenty-two minutes, five photographs were obtained. It would be easy to have two or three photographic apparatus with an operator in the car for each, and thrs to obtain a series of views. By this method a series of topographical documents of incomparable precision might be obtained. Amongst the views taken during this ascent those which are perfect in point of clearness are those taken at the moment when the rays of the sun fell directly on Paris. Good light is absolutely indispensable, and, in spite of the photographs being instantaneous, the car should be kept perfectly free from oscillation at the moment the picture is being taken. The operator and occupants of the car must at that moment remain perfectly still. The movement of the balloon has no injurious effect on the clearness of the proofs obtained; in the present instance the current of air was somewhat rapid, for the balloon traversed Paris at its greatest width, 11 kilometres, in thirty-two minutes. The rapidity of the wind increased subsequently to much more than this. After taking photographs of the earth below, the apparatus was turned upwards to obtain views of the clouds; but the white clouds which reflect the rays of the sun with great intensity, did not give good results. The apparatus will require special arrangement for this work, and in their next expedition the aeronaut-photographers hope to obtain something more complete than they have done. Their experience on the whole is that photographs may be obtained in a balloon as beautiful and clear as the best produced on terra firma. Thanks to the instantaneous process, to the extra-sensitive plates produced to-day, and to other modern improvements, aerostatic photography has a great future. It will give plans which will exceed in precision and clearness the most pains-taking maps; it will be a powerful ally of military art, for it will admit of obtaining a reliable plan of fortresses or of hostile works. At a height of 600 metres a balloon has nothing to fear from artillery fire, and the photographer can operate as safely in his car as in his studio. It will also add to the resources of photography, for there are no places on the earth's surface inaccessible to a balloon.