THE SMITHSONIAN INSTITUTION. 239 



light and transient, not affecting an ordinary vane. Besides, many of 

 the observations placed in this column in my journal are due to the in- 

 fluence of the bay, from which a gentle current — really a sea breeze — 

 frequently flows upon the city for a brief period in the forenoon, before 

 the general current "from the ocean sets in from the opposite quarter. 

 These bay currents are strictly local; and on the opposite side of the 

 bay they take the opposite direction, and swell the proportion of sea 

 winds i.i that location. 



The following table is a summary of three daily observations, con- 

 tinued through the 3'ear 1851, showing the direction of the atmospheric 

 currrents, with reference to their comparative force. 



N. &N.W. E. & N.E. S. &S.E. W. & S.W. 



Nearly calm 49 24 49 30 



Light breeze 86 39 88 146 



Breeze 69 5 36 335 



Wind 20 13 191 



High wind 2 2 29 



Very high wind 3 1 



Thus it appears that the wind was very high only on three days in 

 the year. Much as is said of the violence of the wind at this place, 1 

 have never yet witnessed a wind in California equal to that which fre- 

 quentl}^ attends a thunder-gust or an easterly storm of the highest grade 

 in the Atlantic States. 



From the east quarter of the compass the current did not rise be3^ond a 

 moderate breeze in the entire year, and only for five observations did it 

 reach that degree offeree. As we recede from that limit, either north- 

 ward or southward, the winds increase both in frequency and strength. 

 But it is not until we pass the north point on one hand, and the south- 

 east point on the other, that the}^ are high. Of the twenty observa- 

 tions above noted as "winds" from the north and northwest, seventeen 

 were fi'om northwest, and only three from north. The two high winds 

 under the same head were from northwest. So in regard to the thir- 

 teen winds, three high winds, and two very high winds, in the column 

 headed south and southeast; a small proportion were fi^om due south- 

 east, the mass of them coming fi-om south-southeast and south. The 

 high winds of wmter, when such occur, are from this quarter, and bring 

 rain. The high winds of" summer are always westerly, and without 

 rain. 



In the course of the year there were 169 windy days. On ]23 of 

 this number, the wind did not rise till after the sun had crossed the 

 meridian, and it continued after sunset on 57 only. There were but 20 

 days in the 3'ear windy at sunrise. 



The sea breeze of summer, which forms the most striking trait of the 

 climate of San Francisco, demands something more than a passing 

 notice, and will be reserved for another chapter, together with the sub- 

 jects of clouds, rains, electrical phenomena, &c. 



