LAM
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LAM
Lammas is by some derived from a Saxon word,signifying loaf-mass,because, on that day the Anglo-Saxons made an offering of breadmade with new wheat.
LAMO, an island and kingdom of Africa, on the coast of Me-linda, in Zanguebaiv It lies between the Isle of Pate, and CapeFormosa.
LAMP, [xre/.Mrra;,] a vessel containing oil, with a wick for thepurpose of affording light. Lamps were in general use amongstthe Jews , Greeks, and Homans. The candlestick with sevenbranches, placed in the sanctuary by Moses, and those which So-lomon afterwards prepared for the temple, were cry stal lamps till-ed with oil, and fixed upon the branches. The lamps or candle-sticks used by the Jews in their houses w'ere generally put into avery high stand on the ground. The lamps used at marriage-fes-tivals, alluded to in the parable of the ten virgins, (Matth. xxv. 1,2,) were of a different kind. According to antiquaries, they werea sort of torches, made of iron or potter's earth, wrapped aboutwith old linen, and moistened from time to time with oil. Thelamps of Gideon’s soldiers were of the same kind. The use ofwax was not known to the llomans, but they generally usedlamps; hence the proverb Tempus et oleum perdidi, 1 have lostmy labour. Lamps were sometimes burnt in honour of the dead,both by Greeks and Homans. The utility of lamps in domesticbfe is universally acknowledged; we shall, therefore, notice suchinventions or improvements relative to this braneffof manufacture,as are most approved. The first we shall notice is, that of M.Argand, who obtained a patent in 1784: the superiority of hislamp depends on the admission of a larger volume of air to theflame, than is practicable on the common plan. This object iseffected by' employing a circular wick, so that a strong current ofair rushes into the cylinder round which the wick is placed, andbins, together with the atmosphere, excites the flame to such a de-gree, that the smoke is entirely' consumed. 'Fire light and heatare by this method remarkably increased, while the expence offoe oil is considerably reduced; because those particles, which,! u the usual lamps, are dissipated in smoke, will, by M. Argand’sinvention, be converted into a brilliant iiame. A patent was ob-tained in 1787, by Mr. Peter Keir, for a contrivance of raising thesupply of oil in lamps. The whole effect is produced by the ap-plication of another fluid, the specific gravity of which is greaterfoan that of oil; and which communicates with the latter, byt^eans of certain receivers, tubes, or conductors. These are so^'ranged, that the heavier liquid may press a column of oil up-fords to any requisite height, for the purpose of supplying thea mp. Farther, by prolonging the conductor of the heavier fluid
e *iealh the lower surface ot the column of oil, the weight of the°inierwill hydrostatically act upon such surface, and raise the
°lumi). Thus, the lamp will not only be furnished with the
Purest particles of oil from the upper part, but the flame will also. P considerably elevated above the body of the vessel; and, be-aff s,1 Ppl'ed from a contracted surface of oil, it wilf consequentlyslvi" 1 ' a nlore diffused light, with a considerable diminution of
aue. p' 0r a more minute account of this ingenious contrivance,J/efer the inquisitive reader to the eighth volume of the lleper-Arts and Manufactures. Messrs. White and Smethurstfor--'" ''^proved Argand’s lamp, for which they obtained a pa-th V 11 1800. 'Fhe whole is modestly called an improvement c
, - (ovu. i tie wnoie is modestly called an improvement onfoe burner of the common Argand lamp; the object ot_which)? > fo afford a more free and plentiful supply of oil to the ignitedPurt of the wick ; so that it will burn better, require less frequentfouffi n g ) aiK ; answer well, even with oil of an infenoi quality.M'Cse advantages arc obtained simply, by leaving a larger Uian“ e usual space between the two tubes, within winch the wick isP‘ a ced, Yet it is necessary to contract such space towards thefop. in order that tire burnt’erust or cinder may be more convem-htly removed; an object which maybe effected by applying a“»g or piece of metal, conically or otherwise formed, so as to re-uce the space in the upper part of the lamp to the usual dimen-'ons. The advantages of Messrs. White and Smethurst s im-provement, are: 1. That the inconvenience hitherto complainedot > respecting the mode of cleaning and dressing the lamps, is thusremoved; as, upon their plan, the capillary tubes of the cotton-- yck are prevented from being (it any. time obstructed by the vis■i nature of the oil, while its ascent is promoted by such capillary'sUraction. 2. The quantity of oil consumed by these improvedvo^.m.—No. 119 .
lamps is, by the patentees, stated to be less, in the proportion of atleast four to five, 3. One of the most important advantages thencederived is, that of the wick being rendered tit to burn commonwhale, or seal-oils, which' are sold at about half the price of thebest spermaceti oil, the only inflammable fluid hitherto used inArgand’s lamps; while the former produce an equal degree oflight. Lamps, in many respects, are far preferable to candles,especially for sedentary and studious persons; but as the lightemitted by them is frequently too vivid for weak, or irritable eyes,we would recommend the use of a small screen, which should beproportionate to the disk of the flame, and be placed at one sideof the light, in order to shade it from the reader’s eye, withoutexcluding its effect from others, or darkening the room. Such acontrivance is equally simple and useful: it may consist either ofpaper, or taffety, slightly gummed ; and, being easily folded andcarried in the pocket, is far superior to the common screens.From experiments made some years since, with the express viewof ascertaining the expence of burning chamber-oil, it appears thata common taper-lamp, with eight cotton-threads in the wick, con-sumed in - one hour parts, or about one-third of an ounce ofspermaceti oil, which at that time cost 2,9. 6d. per gallon ; so thatthe expence of burning for twelve hours, amounted to 4*57 far-things, or about 1-t of a penny . The light emitted by such lamp,was as clear and bright as that yielded by candles, which run fromeight to ten in the pound. Subsequent trials were made with M.Argand’s lamp; the result of which was, that the hitter wili conti-nue to burn three hours for the value of one penny. And thougha candle, when newly snuffed, may appear to be preferable, yetthe lamp'is ultimately superior, both for steadiness and durabilityof light. Nay, one good lamp proved equal in its effect to half adozen tallow-candles, consisting of six in the pound, the expenceof which was eight-pence, while that of the lamp amounted onlyto two-pence halfpenny, in the space of seven hours.
Lamp, Perpetual. The testimonies of Pliny , St. Austin, andothers, have led many to believe that the ancients had inventedperpetual lamps; and some moderns have attempted to find ontthe secret, but in vain. Indeed'll seems no easy matter to findout either a perpetual wick, or a perpetual oil. The curious mayread Dr. Plot’s conjectures on the subject in the PhilosophicalTransactions , No. 166; or in Lowthorp’s Abridgement, vol. iii.p. 636. But few, we believe, will give themselves the trouble ofsearching for the secret, when they consider the credulity of Pliny and St. Austin. Their testimony is not a sufficient inducement tous to believe, that a lamp was ever formed to burn 1000 or 1500years; much less is it credible that the ancients had the secret ofmaking one burn for ever.
Lamp, Polling. See Plate XCVII. fig. 4. A machine AB,with two moveable circles, DE, FG, within it; whose commoncentre of motion and gravity is at K, where their axes of motioncross one another. If the' lamp KC, made pretty heavy andmoveable about its axis HI, and whose centre of gravity be-low K, be fitted within the inner circle, the common centre ofgravity of the whole machine will fall below K ; and by reason ofthe pivots A, B, D, E, II, I, will be always at liberty to descend:hence, though the whole machine be rolled along the ground, ormoved in any manner, the flame will always be uppermost, andthe oil cannot spill. In this manner they hang the compass atsea; and thus should all the moon-lanterns be made, that are car-ried before coaches, chaises, and the like.
Lamp-black, one of the black colouring matters. SeeColour. When lamp-black is combined with oil, so as to farma black varnish, it appears from various experiments, that bodiespainted with this compound resist the effects ot electricity in amost surprizing degree ; and that they have, in a variety of cases,even repelled lightning.
Lamp-Furnace. See Chemistry.
LAMPAS, in farriery, denotes an exfcrcscence in the roof of ahorse’s mouth, which is sometimes so luxuriant that it grows abovethe teeth, ami thus prevents his feeding. See Farriery .
LAMPEDOSA, a pleasant and fertile island, though not inha-bited, in the Mediterranean, near the coast of Tunis , about twelvemiles in circumference, 63 miles W. of Malta . Lon. 11 . 0 . li.Lat. 35, 40. N.
LAMPREY. See Petromyzon.
LAMPSAC1US, au epithet for any thing belonging to Lam p-3 F rue us.