CLIMATOLOGY OF NEW HAMPSHIRE. 



127 



Maine. The isotherm of 44° on the west, is a sharpe curve beginning 

 at North Charlestown, and it has its further limit in Danbury. On the 

 eastern border of the state there is a short curve on the Saco in Conway. 

 The isotherm of 43° is similar in shape to that of 44°, but is some ten 

 miles northward. 



The isotherm of 42" begins on the Connecticut in Plainfield, and 

 extends eastward, but is soon deflected northward, passes above the White 

 Mountains, through Randolph, Gorham, and Shelburne. The isotherm 

 of 41° is just below Hanover. Westward in Vermont it is deflected 

 southward ; but in New Hampshire it is nearly parallel with 42°, except 

 that from Lisbon a branch goes almost directly north to Lunenburg, Vt. 

 The isotherm of 40°, the lowest mean average in the settled portions of 

 the state, begins near North Stratford, and probably extends eastward to 

 Umbagog lake. As we ascend the mountains the mean annual tempera- 

 ture decreases rapidly, so that on the summit of Mt. Washington we have 

 an isotherm of 25°- 



Chart II. Referring to chart H, we have isotherals, or lines of equal 

 summer temperature ; and isochimenals, or lines of equal winter tem- 

 perature. For the isotherals, we have a small area about Manchester, 

 included within the line of 70°; there is also an isotheral of 70°, extend- 

 ing along the northern border of Lake Winnipiseogee, thence through 

 Ossipee to the line of Maine. The isotheral of 69° is below Rochester, 

 and there is a more extended area of the same through Tamworth, Madi- 

 son, and Eaton. The isotheral of 68° corresponds with the isotherm of 

 47". The curve of 6'j'^ is the most variable of all the isotheral lines. 



It begins at the Connecticut, near Claremont, is deflected southward 

 to Francestown, then northward to Barnstead, then southward again as 

 far as Exeter, when it turns north and passes between Dover and Great 

 Falls. The curve of 66° begins on the coast near Portsmouth, and 

 passes up the Piscataquis to Dover, where it is deflected eastward. 



The isotheral of 65 ° passes up the river from Hanover, thence up the 

 Ammonoosuc, — makes a sharp curve to the Connecticut, at Lancaster, 

 then runs through Randolph, Gorham, and Shelburne ; that of 64° runs 

 through Stoddard, Nelson, Dublin, and Peterborough; that of 63° begins 

 in North Littleton, goes northward through Lunenburg, Vt., and then is 

 deflected eastward and across New Hampshire, near the Grand Trunk 



