WEATHER. 



the ftrength of the winds, by o, I, 2, 3, &c. and the quan- 

 tity of rain, as it fell through a tunnel, in pounds and 

 centelimals. 



Phenomena of the Weather, Oftober 1697. 



We have feveral fchemes for keeping meteorological 

 journajs or diaries of the weather, extant in the Philofophi- 

 cal Tranfa£lions, the Medical Effays of Edinburgh, and in 

 other books. The Ephemerides Ultrajeftinx may alfo be 

 confulted. The inftruments requifite for fuch journal are, a 

 Barometer, Thermometer, Aneritojcope, and Ombrometer, which 

 fee in their proper places. See a CoUeftion of ingenious 

 obfervations, and meteorological conjeftures, by Dr. Frank- 

 lin, in his Experiments, &c. p. 182, &c. See Evapora- 

 tion, Rain, and Wind. 



We fhall here fpecify fome of the common indications of 

 changes of weather that may be obferved at fea. Under 

 the article Tides we have already ftated, that they are raifed 

 by the joint aftions of the fun and moon ; the fpnng-tides 

 being raifed by the fum, and the neap-tides by the differ- 

 ence of the aftions of thefe bodies ; and, alfo, that the fpnng- 

 tides, near the time of an equinox, are higher than at other 

 times of the year. Now, fince the atmofphere is a fluid 

 much lighter than water, it mud, therefore, be more affedled 

 about the times of new and full moon, and in the months of 

 March and September, than at other times. This is con- 

 firmed by obfervation ; for, about the times of new and full 

 moon, an alteration in the ftate of the weather ufually 

 happens ; and the violent gales about the time of the 

 equinoxes, called equinoxtal gales, are well known, and ex- 

 pefted by every feaman. 



According as the ftate of the atmofphere is more or lefs 

 difturbed, it is evident the appearance of the heavenly bodies 

 will be more or lefs altered. Thus, if the moon appears 

 paler than ufual, or if there is a halo about the moon, rain 

 will probably follow foon after. Several circles about the 

 moon portend wind. Thefe obfervations are alfo applicable 

 to the fun. If the moon appears of a red colour, or if the 

 moon's horns are blunt, they are figns of wind, which may 

 be expefted from that quarter to which the blunteft horn is 

 direfted. In viewing the moon with a telefcope in a quiet 

 evening, if one part of the moon's limb be obferved to be 

 tremulous, while the oppofite part of the limb is without the 

 leaft apparent tremor, the wind may be expefted from that 

 point to which the limb free of tremors is direfted. A red 

 circle about the moon towards the time of full moon in- 

 dicates wind. 



One of the bell known figns in the heavens is the Ra'in- 

 boiu ; which fee. When the blue and yellow parts of the 

 rainbow are very bright, or if all of it vanifh at the fame 

 time, it will be fair weather : if the bow appears to be 

 broken in feveral places, tempeftuous weather may be 

 expefted. 



From the various appearances of the clouds, (fee Cloud,) 

 which are vapours floating in the atmofphere, producing rain, 

 hail, fnow, thunder, and lightning, the approaching weather 

 may, in fome meafurejbe predifted. The height of the clouds 

 feldom exceeds a mile ; and the fummits of high mountains 

 are free of clouds. 



When the fky is of a fine blue colour, without any clouds, 

 3 



it will continue to be fair weather ; but if it is of a very 

 dark blue, clouds will be formed, and rain, wind, or fog, 

 will foon follow. 



When the flcy appears very much clouded for fome time, 

 without rain, it generally firft clears up, and then changes 

 to rain. This is accimnt°d for as follows : — The atmo- 

 fphere at that time being replete with vapours, which, 

 though fufficient to intercept the rays of the fun, yet want 

 denfity to defcend ; and while the vapours continue in the 

 fame ftate, the weather will do fo too ; and iuch weather is 

 commonly attended .vith moderate warmth, and with little 

 or no wind to difturb the vapours, and an heavy atmofphere 

 to fupport them, the barometer being commonly high. 

 But when the cold approacheth, and, by condenfing the 

 vapours, drives them into clouds or drop'-, then way is made 

 for the fun-beams, till the fame vaponrs. I)y farther conden- 

 fation, be formed into rain, and fall down in drops. 



If the clouds, in a fummer evening, gradually diminifli, 

 and at laft vanifh, it will be fine weather ; but, if they 

 increafe, and fniall clouds be obferved to move very fwiftly 

 underneath, it will be rain foon after ; or, if the clouds 

 change to a dark colour, thunder may be expefted. 



If the clouds in the weftern hemifphere, at the time of 

 fun-fet, are tinged with a light red and yellow ; or, if there 

 are no clouds, and the (ley, towards that part of the horizon 

 where the fun fets, be of a beautiful red and yellow, it will 

 be fine weather: but if the fun be of a pale colour, or if 

 the clouds change to a dark red, and continue, it will be 

 rain. The clouds tinged with a dark red in the oppoiite 

 hemifphere to the fun, whether at rifing or fetting, prefage 

 wind. 



In winter, when large clouds are obferved with white 

 edges, and a ftrorg blue fl<y above them, it will be hail or 

 fnow ; or probably thefe may be diflblved into rain before 

 they reach the earth. 



When there are two or more ftrata of clouds moving in 

 different direftio;.s, rain generally follows. Many fmall 

 clouds pretty high, and other appearing at the fame time in 

 form of fleeces of wool, deno'e wind. 



A cloud of an oblong form, fometimes called Noah's 

 Ark, feen in a clear flcy, and changing from a fine light to 

 a dark colour, is a fign of rain ; but, if it changes from dark 

 to light, it is a fign of fair weather. 



A fmall black cloud feen in a clear flfy, or feveral fmall 

 clouds coUefting near each other, ar; an indication of wind 

 from the quarter from whence they are obferved to move : 

 alfo, if the clouds are obferved to diverge from a point in 

 the horizon, wind may be expefted from that, or from the 

 oppofite point. 



When ftars of the fecond and third magnitudes are fud- 

 denly obfcured, wind or rain will foon follow. Thofe 

 meteors, commonly called_/ii///nj- ox Jhooting ftars, are ufually 

 the forerunners of wind. 



That appearance in the heavens refembling a portion of 

 the rainbow, but apparently broader than any part of the . 

 arch when complete, and generally known by the name of 

 a Wind-gall, is an indication of an approaching gale. 



The Aurora Borealis, (which fee,) or northern light, is a 

 fign of wind from between the S. and S.W. points, attended 

 with hazy weather, and fmall rain, the gaie generally com- 

 mencing between twenty-four and thirty hours after the firft 

 appearance of the aurora. The violence of the gale, and the 

 time of its commencement after the aurora borealis is feen, 

 and duration, depend, in a great meafure, upon the brightnefs 

 and motion of the aurora ; for the more brilliant the aurora, 

 and the quicker its motions, the gale will happen fooner, be 

 more violent, and of fhorter duration. 



A change 



