LEA 



LEG 



LA'ZULITE. Lapis lazuli. A blue 

 mineral from Styria and the Tyrol, which 

 furnishes the valuable pigment known 

 by the name of ultra-marine. It is a 

 silicate of alumina, soda, and lime, and is 

 sometimes confounded with klaprothite, 

 or blue spar, which is a phosphate of 

 alumina. 



LEAD. A white metal with a blue 

 tinge; the softest of all the durable 

 metals. White lead, or ceruse, is a white 

 substance produced, in the form of 

 flakes, by the action of the vapour of 

 vinegar on lead. It may be dissolved in 

 acetic acid, forming a crystallizable salt, 

 called sugar of lead, from its sweet taste. 

 Red lead, or minium, is the red oxide of 

 lead, a tasteless powder of an intensely 

 red colour. Black lead, or graphite, is a 

 misnomer, being a carburet of iron. 



LEAF OF PLANTS. The leaf is an 

 expansion of the bark at the base of a 

 leaf- bud, prior to which it is developed. 

 It consists of a midrib, on each side of 

 which is a parenchymatous expansion, 

 composed of a double stratum of cellular 

 tissue, separated by vessels. A simple 

 leaf is that of which the lamina or blade 

 consists of one piece only, whatever may 

 be the depth of its divisions ; a compound 

 leaf is that of which the cellular tissue is 

 separated into several portions, each 

 forming a complete blade by itself. 



LEAF-STALK. Petiole. That part 

 of the leaf which connects the blade with 

 the stem. It consists of one or more 

 bundles of fibre- vascular tissue sur- 

 rounded by cellular substance. 



LEAFLET. The designation of each 

 of those small separate leaves, which 

 together compose a compound leaf. 



LEAGUE. The twentieth part of a 

 degree of latitude, or three geographical 

 miles, each of which is the sixtieth part 

 of a degree. The French have two kinds 

 of league; the first consisting of 2000 

 toises, or 2*42 English statute miles ; the 

 second of 2-77 English miles, or 25 

 leagues to the degree ; the former is their 

 legal posting measure. 



League, Nautical. Seamen measure 

 by nautical miles, 60 of which make a 

 degree of latitude, or a degree of longi- 

 tude at the equator ; and three nautical 

 miles m^ke a nautical league, which is, 

 accordingly, 3*45 land or statute miles, 

 or three miles, four tenths, five hun- 

 dredths, which is easily remembered. 



LEAP-YEAR. The name given to 

 every fourth year of the Julian calendar, 

 in which one additional day— the 29th of 

 193 



February— is reckoned. The year is so 

 called, because the day of the month, 

 after February, leaps over a day of the 

 week. The reason for adding a day 

 every fourth year is, because the tropical 

 exceeds the civil year by six hours, which 

 excess amounts, in four years, to one 

 day. See Bissextile. 



LEAST SQUARES, METHOD OF. 

 A method of finding the most probable 

 truth, when a number of discordant ob- 

 servations have been made upon a phe- 

 nomenon. "If three observations give 

 93, 94, and 98, then the mean of the three 

 is 95, and if this be assumed as true, it 

 is also assumed that the errors of the 

 observations were 2, 1, and 3. The sum 

 of the squares of these is 4+1 + 9, or 14, 

 and this is the least possible sum which 

 can be thus obtained. If, for example, 

 we assume any thing but 95, say 95*1, the 

 assumed errors are then 2*1, Tl, and 

 2-9, the squares of which are 4-41, 1-21, 

 and 841, the sum of which is 1403, more 

 than 14."— Pew. Cycl. 



LEAVEN or YEAST. A substance 

 which possesses the power of commenc- 

 ing fermentation in other substances. 



LECO'NORIN. A white crystalline 

 substance procured from the Leconora 

 tarlarea and other lichens, employed in 

 the manufacture of cudbear. 



LEE. An epithet to distinguish that 

 half of the horizon to which the wind is 

 directed, from the other part where it 

 arises, which latter is accordingly called 

 to windward. 



LEE'LITE. A red siliceous stone 

 found at Gryphytta in Westmannia, and 

 named from Mr. Lee of Cambridge. 



LEEWARD. The lee-side of a ship is U-<A>t 

 that half of a ship (divided lengthways), ^ . 



which is opposite to that on which the ^"^iXA 



wind blows when it crosses her course, 

 and which is called the weather-side. All * 



objects on the lee-side are said to be to 

 the leeward, and those on the weather- 

 side to the windward of the vessel. 



LEEWAY. The angle made by the line 

 on which the ship should run, according 

 to the point of the compass steered upon, 

 and the real line of the ship's way occa- 

 sioned by contrary winds, rough sea, or 

 the set of a current. 



LEGER LINES and SPACES. In 

 Music, the lines and spaces which are 

 added to the staff, when the notes ex- 

 ceed the ordinary compass. 



LEGU'MEN {lego, to gather). A le- 

 gume ; a one-celled, two-valved, superior 

 fruit, dehiscent by a suture along its face 



