The Observatory at St. Martin. 355 



Observations for the purpose of Meteorology, are taken by the 

 usual instruments, at 6 and 1 a.m. 2, 9 and 10 p.m. daily, besides 

 extra hours, on any unusual occurrence. Constant tri-daily obser- 

 vations are also taken on the amount and kind of atmospheric 

 electricity, also on the amount of Ozone, and likewise particular 

 attention is directed to the phenomena of thunder storms — all of 

 which observations are regularly recorded. Besides these daily 

 observations, record is kept of the temperature of springs and 

 rivers and the opening and the closing thereof, by ice ; also on the 

 foliation and flowering of plants and trees, and the periodic 

 appearance of animals, birds, fishes and insects, besides the usual 

 observations on auroras, haloes, meteors, zodiacal light, and any 

 remarkable atmospheric disturbances. 



Many of the instruments, are self-registering and to some the 

 photographic process may be applied, being constructed for that 

 purpose. 



The Observatory is furnished with four barometers. 1. A New- 

 man standard, 0.60 of an inch bore ; the brass scale extends from 

 the cistern to the top of the tube, and is adopted for registration 

 by the photographic process. 2. A Negretti and Zambra's tube, 

 0.30 of an inch bore ; another of a small bore, and also an Aneroid. 

 The cisterns are all placed at the same height (118 feet,) above 

 the level of the sea and are read at each observation. 



Thermometers of Sixes, Rutherford, Negretti, &c, the readings 

 of which are corrected, with the standard instruments of the new 

 observatory, and most of the scales are engraved on the stem of 

 the tubes. Care is taken to verify them twice a year, they arc 

 placed four feet from the ground, and have occupied the same 

 position for some years, being placed free from radiation, and 

 carefully shaded from the sun and rain. 



The Psychrometer, consists of the dry and wet bulb thermome- 

 ters, the scales of which are coincident, and have been carefully 

 read together. There is also a Saussure's hygrometer. In winter 

 the wet muslin is supplanted by a thin covering of ice which 

 requires frequent renewal. 



For solar radiation a maximum Rutherford's thermometer is 

 used, with the bulb kept blackened with Indian ink; the tube is 

 shaded by a piece of glass blackened also with Indian ink, which 

 prevents the index from adhering to either the tube or the mer- 

 cury, as is often the case when not shaded. 



Terrestrial radiation is indicated by a spirit thermometer, of, 



