At other times, free balloons are liberated, carrying sets of automatic registering instruments. 佚名.神奇的知识之书.
An air space of two feet is left between the cover and the balloons. 威廉·亨利·杜利特.世纪发明.
Germany meantime was intensely interested in Count Zeppelin’s dirigible balloons, which, although as long as a battle-ship, had flown with great success. 鲁伯特·萨金特·荷兰.历史性发明.
Two captive balloons had been floated to show the course and also to give an indication of the proper altitude to maintain. 鲁伯特·萨金特·荷兰.历史性发明.
Thinking the English slow to take up the interest in balloons, he wrote that we should not suffer pride to prevent our p rogress in science. 李贝.西洋科学史.
Wireless messages have been successfully sent from aeroplanes, balloons and submarine vessels, and the naval vessels of all nations are kept in easy communication by this method. 佚名.神奇的知识之书.
In communicating between points on land, poles of great height can be used, or captive balloons. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
At these elevated points, whether upon the masts of ships, upon poles or balloons, condensing surfaces of metal or other conductor of electricity are located. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
Small experimental balloons, containing not men, but recording instruments, have gone as high as twenty-two miles. 赫伯特·乔治·威尔斯.世界史纲.
The frame is further strengthened and the balloons stayed by a network of aluminium wire, and the entire frame covered with a soft ramie fibre. 威廉·亨利·杜利特.世纪发明.
For temporary service, as in the case of military operations, the antenna is frequently attached to captive balloons or kites, and so suspended high in air. 鲁伯特·萨金特·荷兰.历史性发明.