METEOROLOGICAL OBSERVATORIES. 165 



be found in M. Angot's masterly Annals, 1889 to 1892; and I Lave been 

 favored by that gentleman with a letter giving- some of his most recent 

 results. It concludes as follows : 



The only general result which is not to be yet found in my annual 

 memoirs is the following: 



The annual variation of temperature on the summit is already found 

 to be very different from that at the level of the soil. The difference of 

 temperature between the lower level and the upper amounts to 1.0° C. 

 (2.9° F.) at its maximum at the end of June, while it is at a minimum at 

 the end of September, when it only attains 0.3° C. (0.5° F.). The annual 

 cooling of the air occurs much more rapidly below than in the upper 

 air, a fact altogether analogous to that shown by the variations of the 

 daily wave of temperature, and it frequently happens that in the months 

 of September and October there is a mean temperature higher, in abso- 

 lute value, at 300 meters altitude than on the ground. The inversion, 

 therefore, which is constantly shown in the hourly means presents itself 

 also in the monthly ones, but only in the autumn, and not in the coldest 

 part of the year. 



The society will be grateful to M. Augot for this preliminary note of 

 some of his important conclusions. 



M. Angot also calls attention to the following fact with respect to 

 humidity: 



Sometimes a process the reverse of evaporation has been noticed on 

 the Eiffel Tower. After a cold period on one occasion, when a sudden 

 warming of the air took place accompanied by great humidity, water 

 rapidly condensed from the atmosphere, so that in three days as much 

 as 9 millimeters (about three eighths of an inch) accumulated in the 

 vessels used for evaporation experiments. Generally speaking, the 

 atmosphere is nearly 8 per cent drier at the top of the tower than it is 

 below. 



Attempts have been made in our own country to secure observations 

 on high towers, but as they have been of necessity confined to much 

 lower altitudes, I must content myself with showing you the picture of 

 the places where the two most notable experiments have been made, 

 viz, Lincoln Cathedral and Boston church tower. 



PRIVATE OBSERVING STATIONS. 



One word about private observing stations. In addition to the tele- 

 graphic reporting stations of the Government, this society has a great 

 number of observers in different parts of the British Isles, whose daily 

 observations are published in our Meteorological Kecord. I show you 

 a view of such a private installation, and in it you may recognize Mr. 

 Mawley, a gentleman of whom you will know more by and by. Mr. 

 Symons tells me that Mr. Mawley's station is so well arranged and 

 conducted as to serve as a type and pattern for all others of the same 

 order. 



CONCLUSION. 



I have now endeavored, as much as has been possible in one brief 

 discourse, to give you some bare information as to observatories in our 



