156 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Pike's Peak Temperature Eecords 



The meteorological observations made on the summit of Pike's Peak 

 extend through the years 1874-1887. It seems to me that the records 

 of this station — situated near the center of the North American conti- 

 nent, at an altitude of 14,111 feet — may be considered as being most 

 reliable material for the study of the influence of the dust veil of the 

 years 1883 and 1884, upon temperature conditions in the United States. 



Table I gives the recorded mean monthly temperatures (5 a. m., 1, 9 

 p. M.) expressed in departures from the corresponding monthly means 

 of the entire series of observations.^" In Figure 1 the consecutive twelve 

 monthly means are represented graphically. On this diagram, one notices 



Fig. 1. — Curve of the consecutive means of temperature observed on the summit of 



Pike's Peak 



immediately that the curve is abnormal between the crests C and E, that 

 in order to have a more regular variation, we ought to have a crest (D) 

 in place of the depression K. Admitting the existence of such a crest, 

 we have intervals of 33, 27, about 31 and about 35 months between the 

 ■crests and 30, 33, 25 and 31 months between the depressions. These 

 ligures are similar to those obtained from the records of many other 

 stations. But, as on the curves expressing the succession of consecutive 

 means for longer series of observations — for example those of Batavia, 

 Xew York, Eome, Warsaw and Stockholm, which are at present at my 

 disposal — the pleionian crests do not always reoccur at approximately 

 regular intervals and seem to be missing sometimes, just like the pre- 

 sumed crest (D), the fact that the Pike's Peak cune shows a long in- 



« Annals Astron. Obs. Harvard CoHege, vol. 22, p. 457. 1889. 



