measure in a right line about 271⁄2 miles. All these computations are in Irish miles, which are to English, in the ratio of eleven to fourteen. This county lays between the latitudes of 54° 36" and 55° 12", north, and between the longitudes of 6° 18′′ and 7° 21′′ west. By doctor Beaufort's computation it contains 318,500 acres (Irish), which is equal to 405,363 (English.) According to my survey and computation, the area of this county extends over a surface of 321,600 acres (Irish), which in English measurement is 409,309 acres. On the north it is bounded by the ocean; on the west by Lough Foyle, and the county of Donegal; on the south by the county of Tyrone; and on the east by Lough Neagh, the river Bann, and part of the county of Antrim. Climate. The neighbourhood of the Western Ocean, the height of the mountains which surround us, and whose ranges intersect our county, are causes, which may account for the fall of a considerable quantity of rain. The following tables, though prepared for a former work, will give accurate and particular information on this subject. During the extraordinary frosts of January last, (1814) the thermometer fell, in some nights, to the twelfth and even to the tenth degree. (Fahrenheit.) In the preceding summary, it appears that the maximum annual quantity of rain, in the space of seven years, does not amount to 35 inches; the minimum is below 26 inches, and the mean is 31.118147. The greatest quantity that I have found to fall in this place, did not exceed 36 inches: whereas at Keswick, in Cumberland, the max. amounts to the enormous quantity of 84.6051, the min. to 34.3057, and the mean to 68.5 inches! At Kendal, in Westmoreland, the rates are nearly the same. The medium quantity in Ireland at large, is from 24 to 28 inches.-Taking the annual quantity of rain which falls in the east of England, (rarely less than 18 inches,) and the max. of the west of that country, the average will exceed 51 inches, and we cannot suppose, that Scotland would produce a lower result. The frequency of our showers, and not the quantity of rain, has given rise to the popular notion of the peculiar wetness of Ireland. From the prevalence of the Western and North-western winds, which may be remarked in the above table, the trees along the coasts exposed to these currents of air, are injured in a remarkable manner; all the shoots of the spring growth towards those points are stunted or destroyed, whilst those, in the other aspects, attain to the usual degree of growth. It does not appear, however, that the North-west wind, which is so unfavourable to vegetable, is injurious to animal life. On the contrary, the greatest instances of longevity and health are found immediately on the coast exposed to winds from this quarter: several instances have occurred of men and women living from 90 to 110 years. Experiments on the Temperature of different Springs in the City of London-Derry, made with Fahrenheit's Thermometer. As to the daily variation, the needle gets to the eastward of its meridian, from nine in the morning till two in the afternoon, and it returns at four. With regard to the annual variation, from the best observations and authorities, it may be registered as in the following table. It appears, therefore, that the magnetic meridian is again coming back towards the true meridian in the county of London-Derry. At Dublin in the year 1657, at which time the Down survey was made, the magnetic and true meridian coincided very nearly. According to an observation, made by Mr. Molyneux, in 1695, the variation was seven degrees west. Since which date the following |