Read the given passage and then answer the following questions: 

He had been provided with an eight-inch Hadley sextant by Ramsden with a silver circle graduated at twenty-second intervals and a two-inch Troughton sextant, a kind of pocket edition which he called his snuffbox sextant. It was extremely accurate and very convenient to carry in difficult terrain. His barometers and thermometers had been standardized before his departure with those of the Paris observatory. The longitude determinations were made with a Dollond telescope and a chronometer by Berthoud whose rate of variation had been carefully checked. Three different kinds of electrometer, provided with pith spheres, straws, and gold-leaf, allowed him to observe atmospheric electricity. He also possessed a Dollond balance for the measurements of the specific gravity of sea water, an eudometer for the analysis of atmospheric gases, a Leyden jar and the necessary chemicals and glass bottles as well as a cyanometer designed by Saussure. This was an instrument by which the blueness of the sky could be determined through comparison with prepared gradations of blue colours and correlated with the hygrometrically determined humidity. The magnetic measurements were carried out with a Borda magnetometer, a rather cumbersome instrument.