CONTRIBUTIONS TO METEOROLOGY- 



41 



ward, while a greater dei)rcssioii prevailed at the same time in Dakota, and was a<l vancing eastward. 

 Tliese two centers tliiis approaclied eacli other and became partially blended on the 24tli, but did 

 not I'orni a s'rand depression, jjrobably on acconnt of a general low pressnre, which prevailed at 

 that time over a large portion of the United States, and which resulted in feeble gradients. 



No. 14 continued its abnormal movements for a7i iinnsually long i)eriod, but the time given in 

 the table embraces two i)eriods of movement towards the west, separated by a period in which its 

 motion was eastward, and its abnormal movements were only in part due to the cause here con- 

 sidered. November t! there was a second area of low pressure in the valley of the Mississippi, 

 and this low center partially controlled the winds to a distance of nearly 1,000 miles on its eastern 

 side. This second low was apparently one of the causes which attracted westward the low ]>re- 

 vailing near the Gulf of Saint Lawrence. This seqond westerly movement of the latter low was 

 apparently due in part to another low area, which prevailed at that time in the neighborhood of 

 Hudson's Bay. 



No. 19 was apparently diverted towards the southwest by a second low area, which advanced 

 from California eastward, and which coalesced with the former on the evening of October 28. 



No. lil was similar to No. 8, being apparently diverted towards the northwest by a low area 

 l)revailiug in Dakota, and with which it coalesced August 29. 



No. 26 was a small low near the Atlantic coast, which was apparently attracted by a greater 

 low prevailing in Minnesota, and with which it coalesced. 



II. Sometimes a heavy fall of rain or snow appears to divert a system of circulating winds 

 towards the region of rainfall, and the center of a low area may be thereby carried in an abnormal 

 direction. Table XXII affords several illustrations ofi this principle. No. 1 was a storm of 

 unusual violence, accompanied by very higli winds, and a very unusual fall of rain, and the 

 greatest amount of rain fell on the north or northwest side of the low center. Table XXIII 

 shows the rainfall at twelve stations, as reported at each of the three daily observatioiis for two 

 days. The last column shows the aggregate fall for the entire period of forty eight hours. The 

 center of the low area appeared to be attracted toward the region of greatest rainfall. 



Table ^XUI.— Bain/all October 19.2 to 21.1, 1873. 



Norfolk 



Ljuchbur}; 



Washiugtou 



Cape May 



Baltimore 



Philadelphia 



Pittsburgh 



New York 



Biitfalo 



Rochester 



Oswego 



Kingston, Canada, 



19.2 



0.15 

 . 5.5 

 .13 

 .00 

 2-2 

 .00 

 .51 

 .00 

 .31 

 .31 

 .17 

 .42 



19:3 



0. 50 

 .65 



1.3iJ 

 .44 

 .78 

 .06 

 .51 

 .02 

 .10 

 .44 

 .23 

 .21 



20.1 



0.32 



.32 



1.11 



.77 



1.78 



1.96 



.97 



.75 



.32 



1.19 



1.42 



.85 



20.2 



0.46 

 .11 

 .43 

 .85 

 .86 

 .21 

 .32 

 .10 

 .90 

 1.38 

 1.02 

 .30 



20.3 



21.1 



0.02 

 .07 

 .01 i 

 .31 I 

 .05 I 

 ,.55 I 

 .67 ! 

 .03 

 1.23 i 

 1.20 I 

 ..57 

 .35 



0.00 

 .00 

 .08 

 .00 

 .02 

 .00 

 .33 

 .04 

 .05 

 .49 

 .15 

 .00 



Sum. 



1.51 

 1.70 

 3.08 

 ■2. 37 

 3.71 

 ■2.78 

 3. 31 

 0.94 

 2.91 

 5.01 

 3.56 

 2.13 



No. 5 was a storm similar to the preceding, but less violent. Table XXIV shows the rainfall 

 at seven stations during a period of two days. The greatest rainfall was generally on the north- 

 west side of the low center. 



Table XXIY.— Bain/all June 16.3 to 18.2, 1876. 



16.3 



17.1 



17.2 



Grand Haven 1.03 



Milwaukee i .01 



La Crosse .13 



Alpena .00 



Escanaba ; .33 



Marquette ; .19 



Dnluth .50 



0.00 

 ..38 



1.13 

 .02 

 .37 

 .82 

 .00 



1.08 

 .34 

 .92 

 .13 

 .26 

 .03 

 .51 



17.3 



18.1 



0.28 j 

 .12 

 .15 I 

 .00 1 

 .39 

 .90 

 .44 



0.32 

 .28 

 .43 

 .00 

 .08 

 .04 

 .27 



18.2 



0.18 

 .03 

 .00 

 .00 

 .20 

 .02 

 .00 



S. Mis. 154—6 



Sum. 



8.89 

 1.16 

 2.76 

 0.15 

 1.63 

 2.00 

 1.72 



