METEOROLOGICAL TABLES. 



401 



In the nine years the barometer was : 



Highest, 

 Lowest, 



Boston. 



April 2, 1S44, 30.92 



Nov. 25, 1346, 23.47 



Range, . . 2.4-5 



Greenwich. 

 Feb. 11, 1349, 

 Jan. 13, 1343, 



30.91 

 23.20 



2.71 



By the above tables it appears that, although the latitude of Greenwich is 9 north' of 

 Boston, its mean annual temperature is exactly the same, arid 2 higher than that of our 

 suburb of Cambridge. Moreover, that January and February are at Greenwich about 

 10 warmer, and July and August about as much colder, than here. The great diffe:ei:ce 

 between the climate of Old and New England becomes the more apparent, when it is con- 

 sidered that places o.i the eastern side of North America, in the latitude of 5H, are near- 

 ly uninhabitable ; and that in the vicinity of Quebec (lai. 46 49'), or more than 4 south 

 of Greenwich, the spirit thermometer on the 6th of February last, as it is said, sank to 

 52. or 13 below the point of congelation of mercury ! 



It also appears that the mean annual temperature in Boston is more than 2 higher than 

 t'rit of the hill in Cambridge on which the Observatory is situated. This difference, it, 

 is believed, is usually found between cities and the more open country in llieir vicinity. 

 It is caused, probably, in part, by the numerous fires in the city, but principally by tlie 

 diminished radiation. The difference is much greater during the night than in the day ; 

 as at sunrise, between Boston and the Observatory, it is, on the average. 4 (about 6 on 

 lower and more level situations) ; and at 2 P. M. nearly disappears. It^ moreover, greatly 

 varies; being largest in perfectly clear and calm mornings, much less in those that are 

 windy, and very small in those that are rainy with strong breezes from the S. or S. \V. 

 The greatest difference occurred on January 5, 1341, viz. 15; the thermometer standing 

 at sunrise at Cambridge, at 15; in Boston. 04;; but 15 has been noticed several 

 times. In consequence of this higher temperature durins the night in the city, ihe quantity 

 of snow is here much less than at places only a very few miles west of us; the last frost 

 of spring is a month earlier, and the first frost of autumn a month later; and delicate 

 kinds of grapes, pears, Sec,., are here well ripened, which at a very short distance fail alto- 

 gether. 



TABLES FOR NEWARK, N. J. LAT. 40 45' N., LOXG. 74 10' W. 



BY WM. A. WHITEHEAD. 



I. Summary of Thermometrical Observations. 



*** The thermometers, self-registering, hung about nine feet from the ground, having 

 a northern exposure, protected from rain and reflection. The monthly means are deduced 

 from those of each dav. 



II. Summary of Barometrical Observations, and State of the Weather. 



*** Barometer, one of Troughton's, with an adjustable cistern. The surface of Rain- 

 gauge four feet from the ground. The number of Fair Days derived from the addition of 

 half-days, the general character of each A. M. and P. M. being recorded. Days of Rain, 

 those on which it fell in appreciable quantities. Days of Snow, those on which it fell 



without resrard to quantity. 



34* 



