THE EXPLORATION OP THE FREE AIR. 319 



nished clotli, were coupled tandem to secure greater safety and more 

 lifting power. The first meteorograph, being a combined recording 

 thermometer and barometer, was constructed by Mr. Fergusson, who 

 in November, 1895, united an anemometer with the thermometer. One 

 of these meteorographs was hung to a ring at the point of attachment 

 of the two kite lines to the main line, a method which still obtains. In 

 August, 1895, in conjunction with the Eddy kites there was first used 

 the cellular or box kite invented by Lawrence Hargrave, of Sydney, 

 New South Wales, which was built from a description published shortly 

 before.^ At the present time some form of the Hargrave kite is gen- 

 erally employed at Blue Hill and elsewhere. Notwithstanding the 

 efficiency of these kites, on account of the weight of the large cord 

 necessary to control them and the surface which this cord presented to 

 the wind, it was found impossible to lift the meteorograph to the height 

 of 2,000 feet. During January, 1896, following Archibald's example 

 and the methods of deep-sea sounding described by Captain Sigsbee, 

 U. S. N., steel pianoforte wire was substituted for cord, and with this 

 wire, which, although lighter and smaller, had greater strength than 

 the cord, the height of a mile was reached in July and a mile and three- 

 quarters in October, 1896.^ 



Up to this tinie a reel turned by two men sufficed to draw down the 

 kites, but with the increasing pull and length of wire recourse to steam 

 was necessary. In January, 1897, a grant of money was allotted from 

 the Hodgkins fund of the Smithsonian Institution for the purpose of 

 obtaining meteorological records at heights exceeding 10,000 feet. 

 With this grant a steam windlass was built by Mr. Fergusson with 

 ingenious devices for distributing and measuring the wire, but the 

 cumulative pressure of the successive coils of wire finally crushed the 

 drum. Our next apparatus was copied from the deep-sea sounding 

 machine of Sir William Thomson (now Lord Kelvin), and with it records 

 were brought down from the prescribed height in October, 1897. Two 

 meteorographs were made by J. Eichard, of Paris, that recorded three 

 elements, viz, atmospheric pressure (from which the height of the instru- 

 ment can be calculated), air temperature, and relative humidity. The 

 first of these meteorographs was ordered in 1896 on the model of one 

 carried by French aeronauts; but since for use with kites lightness is 

 all essential, M. Richard constructed his triple recorder for the first 

 time of aluminum and thereby reduced its weight to 2| pounds.^ 



The kites and apparatus now used at Blue Hill are as follows: The 

 kites generally have two rectangular cells covered with nainsook cloth, 

 excejjt at their tops and bottoms, and one is secured above the other 

 by four or more sticks. The wooden frames are as light as possible, 

 but are made rigid by guys of steel wire which bind them in all direc- 



1 Engineering, February 15, 1895. 



2 Monthly Weather Review of United States Weather Bureau, September, 1896. 



3 La Nature, February 8, 1896. 



