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* LIMEN. 27-1 LIMESTONE. ■whether for pleasure or for unpleasantness. All stimuli of this kind are ealU-d suliliniinal. On the oUier lianil, stimuli of a certain uilen^-ily or duration or extent, and oecurrentes of a certain imporlance, never fail, under ordinary eireum- stances, to evoke a conscious response; such stimuli are called supraliminal. Between the two lies the stimulus which is just able, in a given ease, to arouse a sensation or set up an alVeetion: this just noticeable stimulus is called llie stimulus Umcii. In the sphere of sensation the limen mav be intensive, extensive, nualitative, or temporal. ' We may seek to dilermine, e.g. the least intensity of pressure that will excite a sen- sation in the eutaneoiis pressure-orpans, or the least inlensilv of scmnd that can sliU be heard; the smallest "extension of pressure or of hpht that is able, under constant conditions of dura- tion and intcnsitv, to produce sensation; the least number of air-vibraticms that can arouse the tonal quality to which their period corre- sponds; the least duration of a given color or temperature that can evoke its approiniate sen- sation. In every ease the limen is the just sensible minimum of stimulation. The affective liniens. owing in part to dillieulties of experi- mentation, but chielly to the dependence of the affective reaction upon the whole contents of consciousness, have not been worked out. (2) What holds of stinuili holds also of ditTerenees between stimuli. Two colors may be so nearly alike as to be sensed identically; the stimulus difference is snl)limiiial. Or. they may be so dif- ferent as, normally, to be sensed differently; the stimulus difference is supraliminal. Be- tween the two lies a color difference that, in the given case, is just noticeable; such a difference is called the difference limen. The ascertainment of this value is of extreme importance in psycho- physics; its absolute or relative constancy de- termines the absolute or relative constancy of the sensible discrimination. (See DISCRIMIN-V- Tiox, SENSini.ii.l The most elaborate of the psychophysical measurements methods are con- cerned with it. See Psvcitoniv.sics. The stimulus limen is. evidently, at the same time the limen of consciousness. Wundt distin- guishes from this a limen of attention or of apperception. -Sny imjiression which has passed the limen of stini'ulus (i.e. of consciousness) is able, "provided the subjective factor of attention be superadded." to |)ass the limen of •clearness'; and there are many degi-ees of clearness, as there are many degrees of su])raliminal stimulus-value. While, however, we cannot question the the- oretical significance of a distinction of the two limens, it is exceedingly doubtful whether con- sciousness is capable at any one time of more than two desrees of clearness. See Attention. Consult: Ilerbart, Werke. vol. v. (Leipzig. 18Sf.) ; Fechner. Elemenlc der I'siichophysik, vol. i. (ib., ISSO) ; Wundt, Pliy.iiolofiisehe Pst/chologie (ib., 100-2) : Kuelpe. Outlines of Psiicholofi;/ (New York, ISO.i). LIME PLANTS. Plants which grow natural- 1 in soils or rocks rich in calcareous com- pounds. See Rock Plants. LIM'ERICK. An inland county of the Prov- ince of IMunstcr. Ireland, separated by the Shan- non on the north from Clare, and boundedeast bv Tipperarv. south by Cork, and west by Kerry (Map: Ireland, C 4).' Area, 1064 square miles. A mountainous district on the west belongs to the great coaltracl of .Munster, Imt the coal is of ail inferior quality, and is chielly used for the burning of lime. The soil in general is fertile, especially in the district called the Golden ale. The capital is Limerick. Population, in 1841, 331,000: in ItiOl, 14ti,000. LIMERICK. A city, civic county, and jiorl. capital of County Linierick, Ireland, on the Shannon, 120 miles west-southwest of Dublin (Map: Ireland, C 4). It occupies both sides oi the river, together with King's Island. It is divided into the English town, the oldest part of the city connected with the extensive suburb of Tliomond Gate on the Clare side of the Shannon, and the Irish town, which exlen<ls on the south bank of the river into Newtown Pery, the best part of Limerick. The gas-works, water-suiiiily, and other public utilities are municipal property. mon<' the noteworthy buildings are Saint .John s Catholic Cathedral a'nd S;unt Mary's Anglican Cathedral. Limerick is a military station for in fantry, artillery, and cavalry, with barracks within the wall's of King .Tohn's Castle, an im- portant and well-preserved old Norman fortress defemlins Thomond Bridge. The Shannon, crossed by several bridges, is navigable for ships of larg. biii-den, and is connected with Didilin by th.- Griind Canal in Kings County, and the Koyal Canal near Longford. The river is canalized to the head of Lough Alh-n. The graving-dock ad- mits vessels of 2.500 tons, and there is a patent slip for vessels of 500 tons, and :i floating dock for vessels of ."iOOO tons. The industries include the mainifactui-e of the eelebi-at<.d Limerick fish- hooks. Hour-milling, biieon-enring, lace-manufar turing. tanning, etc. A large import trade i- carried on to the value of between £800,000 and £000,000 annually, Linierick ranking fourth among Irish ports! The chief export is oats; im- ports," grain, petroleum, sugar, and timber. The United States is represented by a consular agent. The ancient Regia of Ptolemy. Limerick, from its position on the Shannon, was long an object nf desire to the Danes, who occupied it m the inuhll of the ninth century, and held possession till v dueed to ;i contributary condition by Brian Boro imhe in the tenth century. It was early occu]n. d by the Kn"lish, and in 1210 King John visited a'nd fortified it. It was assaulted and partially burned in 1314 by Edward Bruce. It was oc- cupied by the Catholic party in 1641. but sur- rendered' to Ireton in 1G.5I. At the Revolution, it was the last stronghold of King James. Hav- in" been unsuecessfuUy besieged by illiam afFer the victory of the Boyne. it was regularly invested in 1601 bv General (iinkcl. and after a vigorous and brilli:int defense of several weeks, an"armistice was proposed, which led to the w^ell- known 'Treaty of Limerick,' the alleged viola- tion of which has been the subject of frequent and acrimonious controversy between political parties in Ireland. The so-called 'treaty stone still marks the spot, near Thomond Bridge, nt the entrance of the suburb, near Thomond Gate, where this treaty w-as si.gned. Population in ISOI. 37,1.5.5: in ioOl. 30.873. Consult: Lenihan. Limerick. Its Bistor;/ and .intiquilics (2d ed.. Dublin. 1884). LIMESTONE. The name given to rocks which are composed of carbonate of lime, and sometimes also of carbonate of magnesia The purest limestones known contain nearly 100 per