549 



Paspalum distichnm^ P. lividum, P.puhijlornnij Phalaris intermedia, vnr. 

 anguHta^Pappophorum apertum, P. wriyJitiij k^ehcdonnardiifi texaniis, Scler- 

 o)}<)(lon karwinslcianus, Sporoholus ar(/utuN, *S'. huckleyi, 8. interrupt u.s, S. 

 trichohpi.s, S. wrif/htii, Stijxt pnuiata, 8. scrib)ieri, Tricliloris plurijlora, 

 T. ccrtieiUata, Triodia acuminata^ T. albescens, T.eratjrostoides, T. f/randi- 

 Jlora, T. neallei/i, T. pulchella, T. stricta, T. tcxana, T. trinerviykimis^ 

 Triseiuni hall it, T. interruptum. 



WEATHEE BUREAU. 



Monthly AVeatheii Review, Vol. XIX, Xo. 10, Ootorer, 1891 

 (pp. i;33-2r)8, cliai'ts (i). — Besides the data lor October on the topics 

 rejiulaily treated in this publication, there is a sliort article by H. A. 

 llazen containiiii;- some general statements witli reference to tlie fluctua- 

 tions of temperature and i>ressure at the base and summit of Mount 

 Washington in Xew Hampshire, which have been represented in charts 

 in several recent numbers of tlie Keview. Tlie substance of this arti- 

 cU^ is as follows: 



The last chart in this Review eontaius a continnatioii of tlie curves previously pub- 

 lished, and completes these fluctuations for the mouths of January, February, and 

 March, from 1871 to 1886, or for 16 years. 



(1) An interesting question arises as to the efiect of the mountain upon the tempera- 

 ture of the air. The curves seem to show that if there is any effect it is exceedingly 

 slight and can not influence the maximum and mininmm points, excejit to prevent 

 the extreme rise and fall in warm aud cold waves tliat might occur in the free air; 

 [u other words, the temperature in a warm wave might not rise quite so high if the 

 summit were cooler than the air and might not fall quite so low in a cold wave if 

 the sinnmit rocks were warmer than the air. It would appear that under any and 

 nil circumstances the dips and rises in 1 he fluctuations of temperature at the summit 

 would not be shifted ai)preciably in time of occurrence by the presence of the moun- 

 tain. 



(2) Is the diurnal range entirely eliminated from the base curve? It will be noted 

 that the base curve shows a great many minor fluctuations of temperature not to be 

 found in the summit curve, aud a close inspection will show that many of thesfl are 

 due to the diurnal range. For example, with a clouded sky the diurnal range has 

 been overcompensated, since the clouds prevent radiation at night and isolation by 

 day. These cases, however, are very few and the eifects are not sufficiently strong 

 to obliterate the larger fluctuations. 



(3) As was to be expected, the fluctuations of pressure are almost exactly identical 

 at the base and summit. Occasionally the change in temperature at the summit has 

 preceded that in pressure to such an extent as to cause the pressure phases to lag 

 behind at the summit. 



(4) As has been noted before, the most marked characteristic in the temperature 

 curves has been their closeness at base and summit, indicating apparently a general 

 effect, not essentially modified by local causes. The earlier change at the summit in 

 both cold waves and hot waves is remarkable and does not seem to be due, as has 

 been suggested, to the greater rapidity of the upper current which carries the warm 

 or cold air from the west more rapidly to the summit than to the base. It will be 

 seen that any eff"ect of this kind would be very quickly obliterated by the motion of 

 the air. Again, while on some accounts warm air from the earth's surface might 

 produce such an effect, it would seem that cold air could not have this source, but 

 must come from above. 



Observations are much needed at very much greater heigiits, even up to 30,000 feet, 

 in order to settle thes;^ and many other ({ucstious. 



17^50— No. 8 4 



