Scientific Intelligence. — Meteorology. 181 



continue to blow for six or ten weeks. It is very curious, that 

 whilst, to the natives, and to the Europeans, who, from long re- 

 sidence, may be said to be acclimated in the settlement, these 

 winds are exceedingly annoying, the Europeans newly arrived 

 consider them as refreshing and salubrious. But during the 

 raging of the harmatans, the furniture of every house is covered 

 with fine sand, and tables and chairs crack under their influence. 

 Mr Boyle concludes this part of his subject by a diary of the 

 weather at Sierra Leone, for the term nearly of a year, — a docu- 

 ment that will be read with extreme interest by all the cultiva- 

 tors of meteorological science. 



8. On the distance to which Spray of the Sea may he carried. 

 — A few remarks on the distance to which spray from the sea 

 is sometimes carried inland by storms of wind, may not^ per- 

 haps, be deemed altogether irrelevant to the subject we are 

 treating upon. Sea-water is brought into the immediate neigh- 

 bourhood of Manchester, which is at least thirty miles from the 

 nearest coast, by every violent and long continued gale from the 

 west ; and the exact proportion in given quantities of rain-water, 

 collected on several occasions of this kind, has been determined 

 chemically. That the sea is the principal source whence the 

 salt is derived, with which the rain that falls in this town and 

 its vicinity is occasionally impregnated, cannot, I think, be 

 doubted ; as I have clearly ascertained, by direct experiment, 

 that its excess or deficiency depends entirely on the direction, 

 force, and duration of the wind. Rain collected in clean glass- 

 vessels, a few miles to the north of Manchester, when the wind 

 blows moderately from the north or north-east, scarcely ever 

 exiiibits the slightest trace of muriatic acid, on the apphcation 

 of the most delicate test (nitrate of silver), even when reduced 

 two-thirds or three-fourths by spontaneous evaporation ; though 

 samples collected in the town, precisely at the same time, on be- 

 ing subjected to the test, generally have their transparency 

 more or less impaired. This fact seems to prove, that, notwith- 

 standing muriate of soda is never raised into the atmosphere by 

 evaporation, yet the air over large towns usually contains a very 

 minute portion of muriatic acid, which, as Mr Dal ton observes, 

 is probably supplied by the sublimation of muriate of ammonia 

 during the combustion of fuel. A considerable increase of mu- 



