152 METEOROLOGICAL OBSERVATORIES. 



Greenwich is taken as a type; second, observatories in high places; 

 and, third, a few notes on private observing stations, with perhaps some 

 suggestions as to what may still remain to be done. 



ROYAL OBSERVATORY, GREENWICH. 



A first-order station is one at which continuous observations are 

 taken with self-recording instruments; and I will take you, for an 

 example, to the Eoyal Observatory at Greenwich, where, by the cour- 

 tesy of the astronomer-royal, and with the kind help of our past presi- 

 dent, Mr. W. Ellis, F. E. S., and Mr. Nash, the present superintendent 

 of the magnetical and meteorological department, I have been able to 

 collect a little information. This, although it is not by any means 

 new to many of our fellows, may interest others who may not have had 

 the opportunity of visiting the observatory. 



On entering tbe building, after passing the various establishments 

 devoted to astronomy and horology, we find the meteorological observ- 

 atory snugly placed among the other edifices, and one's first notion is 

 that the situation is much too confined. But it is to be remembered 

 that most of the surrounding buildings have been erected since the 

 establishment of the meteorological department, and that owing to tbe 

 formation of the hill and the small space at disposal, some crowdiug 

 became inevitable. There is room to hope that this will be remedied 

 some day by removing the magnetical and meteorological part to some 

 more commanding site. 



The building containing the principal meteorological instruments is 

 of wood, and of only one story in height. On account of the delicate 

 magnets below in an underground apartment, there is no iron used in 

 the structure, the place of nails being supplied by pegs of bamboo, 

 while the stoves, pipes, and locks are all of copper or brass. 



The building is in the form of a cross and contains several rooms; 

 one is used as a computing room, and in another, larger, is placed the 

 standard barometer and the electrometer. Of the magnets underneath 

 we will speak more anon. We shall first consider the outdoor instru- 

 ments and imagine ourselves personally conducted to take a rapid 

 view of what is going on in the observatory. 



We note first the four thermometers which are sunk in the earth in 

 order to take the temperature at different depths. No. 1 is at a depth 

 of 24 French feet below the surface of the soil. The long and fragile 

 stem of this thermometer was successfully placed in a deep hole in the 

 gravel soil and packed up with sand, adding successfully the 12-foot, 

 6-foot, and 3-foot thermometers. French feet were used, in order that 

 the results might compare with continental observations. During the 

 first two years, 1847 and 1818, the thermometers were read every two 

 hours; but the diurnal variations were found to be very small, and the 

 readings have since been taken only once, daily — at noon. The observa- 

 tions have been discussed by Professor Everett and others. As might 



