310 Meteorological Observations at the Keio Observatory. 



placed alongside of it. Newman's standard has been found to 

 accord with the two large standard barometers of the observa- 

 tory which also agree together. 



Thermometers. — These are supported in a wooden frame, or 

 cage, opposite the north entrance of the observatory, at a height 

 of eleven feet above the ground. The sides of the cage are 

 like Venetian shutters, consisting of flat bars of wood placed 

 horizontally with the upper edge inclining inwards, each bar 

 overlapping the one beneath it, yet so as to leave an inch of 

 clear space between them. The objects of this construction are 

 to exclude rain, while interfering as little as possible with the 

 free circulation of air, and to avoid any possible error arising 

 from radiation. In order still further to guard against the 

 latter source of error, the cage is surrounded by another of 

 similar construction ; they are nearly cubical in form with in- 

 clined close roofs, and open at the bottom. During the heat of 

 the day they are defended from the direct rays of the sun by 

 the observatory building, from the north wall of which the 

 thermometers are eight feet distant. 



The instruments are five in number ; two, the ordinary dry 

 and wet bulb thermometers, placed vertically, with their bulbs 

 six inches apart, and the others, which are self-registering, 

 placed horizontally. The highest temperature is shown by a 

 Phillips' maximum thermometer, in which a small column is 

 separated from the body of mercury by a speck of air ; on 

 increase of temperature the column is forced forwards, but it 

 does not recede when the temperature diminishes, thus forming 

 an index of the highest temperature attained. The lowest 

 temperature is observed by a Rutherford's spirit thermometer 

 (with glass index) of the ordinary construction, and by a 

 Oasella's new mercurial minimum ; the indications of the latter 

 being remarkably consistent with those of the spirit thermometer. 

 Main Gauge. — This instrument is placed on a level with the 

 ground, about eighteen feet above the sea, and exposes a 

 surface of 100 square inches for the collection of rain. The 

 position selected for it, to ensure freedom from obstructions to 

 the falling rain, is near the middle of an enclosure of an acre of 

 land attached to the observatory, where it is 110 feet removed 

 from the nearest obstacle, and 200 feet from the observatory. 



Anemometer. — This is Robinson's arrangement, which con- 

 sists of four hollow hemispherical cups attached to horizontal 

 arms projecting at right angles to each other, from the top of 

 an easily moveable vertical axis. The cups are so placed, that 

 in revolving about the axis the convex side of each of them 

 precedes the concave from whatever direction the wind is blow- 

 ing, the velocity of rotation being neai'ly equal to one third of 

 the velocity of the wind. By the intervention of suitable toothed 

 wheels, the axis (a portion of which forms an endless screw) 



