FIRE, balls of, in meteorology, a kind of luminous bodies, generally appearing at a great height above the earth, with a splendour surpassing that of the moon ; and sometimes equalling her apparent size. They generally proceed in this hemisphere from north to south with vast velocity, frequently breaking into several smaller ones, sometimes vanish ing with a report, sometimes not. These luminous appearances no doubt consti tute one part of the ancient •prodigies, blazing-stars, or comets, which last they sometimes resemble in being attended with a train ; but frequently they appear with a round and well defined disk. The first of these, of which we have any accurate account, was observed by Dr. Halley and some other philoSophers, at different places, in the year 1719. From the slight observations they could take of its course among the stars, the perpendi cular height of this body was computed at about seventy miles from the surface of the earth. The height of others has also been computed, and found to be va rious though in general it is supposed to be beyond the limits assigned to our atmosphere, or where it loses its refrac tive power. The most remarkable of these on record appeared on the 18th of August 1783, about 9 o'clock in the even ing. It was -seen to the northward of Shetland, and took a southerly direction fire an immense space, being observed as far as the southern provinces of France, and one account days, that it was seen at Rome also. During its course it appeared frequently to have changed its shape ; sometimes appearing in the form of one ball, sometimes of two or more ; some times with a train, sometimes without one. It passed over Edinburgh nearly in, the zenith, and had then the appearance of a well-defined round body, extremely lu minous, and of a greenish colour ; the light which it difinsed on the ground giving likewise a greenish cast to objects. After passing the zenith' it was attended by a train of considerable length, which, continually augmenting, at last obliterat ed the head entirely ; so that it looked like a wedge flying with the obtuse end foremost. The motion was not apparent ly swift, by reason of its great height ; though in reality it must have moved with great rapidity, on account of the vast space it travelled -over in a short time. In other places its appearance was very different. At Greenwich, we are told, that two bright balls parallel to each other led the way, the diameter of which ap. peared to be about two feet ; and were followed by an explosion of eight others, not elliptical, seeming gradually to muti late, for the last was small. Between each two balls a luminous serrated body extended, and at the last a blaze issued, which terminated in a point. Minute par ticles dilated !i-om the whole. The balls were tinted first by a pure bright light, then followed a tender yellow, mixed with azure, red, green, &c; which, with a coalition of bolder tints, and a reflec tion from the other balls, gave the most beautiful rotundity and variation of co lours that the human eye could be charm ed with. The sudden illumination of
the atmosphere, and the form and singu lar transition of this bright luminary, tend ed much to make it awful: nevertheless the amazing vivid appearance of the die ferent balls, and other rich connective parts not very easy to delineate, gave an effect equal to the rainbow in the full zenith of its glory.
F311.13, extinguishing of. The world has long been of an opinion, that a more rea dy way than that in general use might be found for extinguishing fires in build ings: and it has been generally attempt ed upon the doctrine of explosion, Za. chary Grey' was the first person who put this plan into execution with any tolera ble degree of success. He contrived cer tain engines, easily manageable, which he proved, before some persons of the first rank, to be of sufficient efficacy, and of fered to discover the secret by which they were contrived for a large premium, given either from the crown, or raised by a subscription of private persons. But the scheme meeting with no better suc cess than things of this nature usually do, he died without making the disco very. Two years after this, the person who had his papers found the method, and it was shown before the King of Po land and a great concourse of nobility at Dresden, and the secret purchased at a very considerable price. Afterwards, the same person carried the invention to Paris, and many other places, and prac tised it every where with success. The secret was this : A wooden vessel was provided, 'holding a very considerable quantity of water : in the centre of this was fixed a case made of iron plates, and filled with gunpowder; from this vessel to the head of the larger vessels contain ing the water, there was conveyed a tube or pipe, which might convey the fire very readily through the water to the gun powder contained in the inner vessel. This tube was filled with a preparation easily taking fire, and quickly burning away ;- and the manner of using the thing was, to convey it into the room or build ing where the fire was, with the powder in the tube lighted. The consequence of this was, that the powder in the inner case soon took fire, and with a great ex plosion burst the vessel to pieces, and dispersed the water every way : thus was the fire put out in an instant, though the room was flaming before in all parts at once. The advantage of this invention was, that, at a small expense, and with the help of a few people, a fire in its be ginning might be extinguished ; but the thing was not so general as it was at first expected'that it would prove, for though of certain efficacy in a chamber or close building, where a fire had but newly be gun, yct when the mischief has increased so far that the house was fallen in, or the top open, the machine had no effect.