534 PHILOSOPHICAL TRANSACTIONS. [aNNO 1768. 



to whose labours the curious stand so much indebted. Customs the most 

 common, in distant countries, are often of all others the least apt to attract the 

 observation of travellers, who, engaged in other pursuits, must be indebted to 

 accident for the knowledge of such things, as the natives seldom talk of, from 

 the belief that they are known to all the world. This consideration may, in some 

 measure, account for inoculation having been overlooked by those who have tran- 

 siently passed through these countries; and is all that can be offered as an apology, 

 for the having remained so long unacquainted with a fact in medical history, 

 in a situation where they had so many opportunities of information. 

 Dated Aleppo, Nov. 26, 1767. 



XXI. On the fVeather, the Barometer, Thermometer, and Magnetic Declination. 

 By Dr. Wolfe, at Warsaw. Dated Warsaw, Jpril 15, 1768. p. 151. 



Our winter has been very long and very severe. The frost was, at a medium, 

 from the middle of December to the middle of March, at Q degrees of Reaumur's 

 thermometer below the freezing point. Three times it was from 19 to 20 

 degrees, and very seldom ascended to the freezing point. Last year the frost 

 was at 24 degrees, but of no duration. In the year 1 740 it was at 26 degrees, 

 which, perhaps, is the lowest it has been remembered in this country. This 

 year we have had little or no snow, which made the frost exceedingly more 

 sensible. The barometer is here, at a medium, at 284- inches Rhinland measure: 

 great storms sink it 2 inches lower; and very dry weather raises it I-l inch higher. 

 The declination of the needle at this place is 1 1 degrees and a half to the west. 



XXII. Extract of a letter from Mr. Peter Wargentin, Sec. of the Royal Acad. 



of Sciences at Stockholm, and F. R. S., dated Feb. 23, 1 76s. 

 As it is related in the public newspapers, that the weather * has been 

 uncommonly cold in G^ermany, England, and France, towards the end of last 

 year, and the beginning of the present year, Mr. W. here sent the degrees 

 of altitude by Reaumur's thermometer, observed since the beginning of Novem- 

 ber, 1767. The altitudes here set down are the arithmetical means of 3 taken 

 every day, viz. in the morning before sun-rise, a little after noon, and at 10 

 o'clock at night. Hence it appears that the cold has been moderate here with 

 respect to this climate, and nothing more than common, though it was without 

 intermission, from the beginning of December. The greatest cold in these 



• The least height of Fahrenheit's thermometer, set down in the coarse of the astronomical 

 observations made at the Royal Observatory, was 15° on Jan. 6', at the transit of Venus over the 

 meridian at 8" 42"" a.m. At which time nearly the same was observed by Lord Charles Cavendish 

 in Great Marlbro'-Street, at 17°. But by a thermometer described in vol. 50, of these Transactions, 

 placed on the top of the same house, in a very bleak situation, Dec. 31, it appeared to have been at 

 12^° in the preceding night; Jan. 3, l6°; and Jan. 6", l6"», Jan. 7, 13"— Nevil Maskelyne.— Orig. 



