MAR 



MAR 





' MARE. See Eatrus. 

 MARGARITARIA, in botany, a genus 

 of the Dioecia Octandria class and order. 

 Essential character : male, calyx four- 

 toothed ; corolla four-petalled : female, 

 calyx and corolla as in the male ; styles 

 four or five ; berry cartilaginous, four or 

 five grained. There is but one species, 

 viz. M. nobilis, found in Surinam. 



MARICA, in botany, a genus of the 

 Triandria Monogynia class and order. 

 Natural order of Ensatse. Irides, Jus- 

 sieu. Essential character : corolla six- 

 parted, with tliree alternate segments, 

 as small again as the others; stigma petal- 

 form, trifid, with the three divisions sim- 

 ple, acute ; capsule three-celled, infe- 

 rior. There is but one species, viz. M. 

 paludosa, a native of the moist meadows 

 of Guiana. 



MARILA, in botany, a genus of the 

 Polyandria Monogynia class and order. 

 Essential character: calyx five-leaved; 

 corolla five-petalled; capsule four-celled, 

 many-seeded; stigma simple. There is 

 but one species, viz.M. racemosa, a native 

 of the West Indies. 



MARINE, a general name for the navy 

 of a kingdom or state ; as also the whole 

 economy of naval affairs, or whatever re- 

 spects the building, rigging, arming, 

 equipping, navigating, and fighting ships. 

 It comprehends likewise the government 

 of naval armaments, and the state of all 

 the persons employed therein, whether 

 civil or military. 



MARINE acid. See MURIATIC acid. 

 MARiJVE-cAaiV, a machine invented for 

 viewing 1 the satellites of Jupiter at sea, 

 and thereby determining the longitude 

 of their eclipses. 



MARINE remains, a term used to ex- 

 press the shells of sea-fishes, and parts of 

 crustaceous and other sea-animals, found 

 ill digging at great depths in the earth, 

 or on the tops of high mountains. Being 

 found in these situations, is an evident 

 and unquestionable proof of the sea hav- 

 ing been once there, since it must have 

 covered those places where it has left its 

 productions. It has been the general 

 opinion, that these marine bodies were 

 carried to the places where they are oc- 

 casionally found by the waters of the uni- 

 versal deluge, described in the Old Tes- 

 tament. There are, however, evident 

 proofs that it cannot have been the cause 

 of all that is attributed to it, and there 

 must have been some other cause of many 

 of these remains having been placed 

 Where we now find them. 



MARINE surveyor, is the name of a ma- 

 chine, contrived by Mr, H. de 



for measuring the way of a ship at sea. 

 The machine is in the form of the let- 

 ter Y, and is made of iron, or other metal. 

 At each end of the lines which constitute 

 the angle or upper part of the letter, are 

 two pallets, not much unlike the figure 

 of the log ; one of which fulls in the same 

 proportion as the other rises. The fall- 

 ing or pendant pallet meeting a resist- 

 ance from the water, as the ship moves, 

 has by that means a circular motion un- 

 der water, which is faster or slower ac- 

 cording as the vessel moves. This mo- 

 tion is communicated to a dial within the 

 ship, by means of a rope fastened to the 

 tail of the Y, and carried to the dial. 

 The motion being thus communicated to 

 the dial, which has a bell in it, it 

 strikes exactly the number of paces, 

 miles, &c. which the ship has run. Thus 

 the ship's distance is ascertained, and the 

 forces of tides and currents may also be 

 discovered by this instrument. See Phil. 

 Trans. 



MARINER'S compass, is an instrument 

 used at sea by mariners to direct and as- 

 certain the course of their ships. It con- 

 sists of a circular brass box, which con- 

 tains a paper card with the 32 points of 

 the compass or winds, fixed on a magnetic 

 needle that always turns to the north, ex- 

 cepting a small deviation, wiiich is varia- 

 ble at different places, and at the same 

 place at different times. The needle, 

 with the card, turns on an upright pin 

 fixed in the centre of the box. To the 

 middle of the needle is fixed a brass coni- 

 cal socket or cap, by which the card 

 hanging on the pin turns freely round the 

 centre. The top of the box is covered 

 with a glass, to prevent the wind from 

 disturbing the motion of the card. The 

 whole is inclosed in another box of wood, 

 where it is suspended by brass hoops or 

 gimbals, to keep the card in a horizontal 

 position during the motions of the ship. 

 The whole is to be so placed in the ship, 

 that the middle section of the box, paral- 

 lel to its sides, may be parallel to the mid- 

 dle section of the ship along its keel. See 

 Plate Miscel. fig. 9. 



The mariner's compass was long very 

 rude and imperfect, but at length receiv- 

 ed great improvement from the invention 

 and experiments of Dr. Knight, who dis- 

 covered the useful practice of making ar- 

 tificial magnets ; and the farther emenda- 

 tions of Mr. Smeaton and Mr. M'Culloch, 

 by which the needles are larger and 

 stronger than formerly, and instead of 

 swinging in gimbals, the compass is sup- 

 ported in its very centre upon a prop, and 

 the centres of motion, gravity, and mag- 



