324 On guiding Balloons 



that mentioned in the last experiment. With the aid of a good 

 telescope, I had also the additional satisfaction of being able to 

 observe the descent. Soon after the balloon became in equili- 

 brio, the spiral motion ceased ; but as soon as ever the balloon 

 began to fall, it was resumed, but in a contrary direction. 



These experiments appear to me to prove in a satisfactory 

 manner the possibility of causing balloons to deviate by a very 

 considerable angle from a perpendicular ascent or descent. This 

 conclusion might be confirmed, if necessary, by analogy from 

 several other contrivances of art founded on the same principle; 

 such as kites, ships sailing with a side wind, &;c. but 1 consider 

 it would be superfluous. 



As I have now described these experiments at full length, it 

 will be but right to mention an inconvenience with which this 

 method of aerial navigation is attended. Perhaps the reader 

 may have anticipated the observation that, to make a balloon 

 proceed to any considerable distance in a given direction, it is 

 necessary it should ascend and descend alternately with great 

 rapidity. In a Montgolfier balloon this may be easily accom- 

 plished by the mere increase or diminution of the fire, and, per- 

 haps, by the addition of a large valve. A hydrogen-gas balloon, 

 on the contrary, could not siistain for any length of time the 

 continual losses of gas and ballast necessary for such repeated 

 ascents and descents. Hence, until some means are discovered 

 of ascending and descending in a hydrogen-gas balloon without 

 loss of gas or of ballast, the present plan is applicable only to 

 Montgolfier balloons. These balloons are generally regarded 

 in England as extremely dangerous, although I am inclined to 

 think the idea arises chiefly from the circumstance that in this 

 country no person has ever yet ascended in one of them. 



The mode of using the plane will perhaps be better under- 

 stood by supposing that we have a large Montgolfier balloon 

 furnished with the necessary apparatus, and that it is required to 

 direct it to a particular spot. It would be requisite that the 

 plane should be furled during the inflation, and the commence- 

 ment of the ascent. When the balloon has risen to a sufficient 

 lieight, the plane is unfurled, and set at an angle of 70° from 

 the perpendicular. The triangular sail is next to be expanded 

 and managed as a rudder until it brings the machine roimd to 

 such a position that the elevated end of the oblique diagonal 

 points towards that part of the horizon to which it is required 

 to direct the balloon. The greatest possible power nmst then 

 be communicated to the machine, which will ascend describing 

 tlie diagonal of a square; and consequently move one mile hori- 

 zontally for every mile of perpendicular ascent. After con- 

 tinuing a rapid ascent as long as convenient, the balloon must 



be 



