SQU 



ST A 



Inner series being called sporangidium, 

 to which the peristomium belongs. A 

 combination of sporangia is termed by 

 the German botanists a sporocarpium, 

 especially when they are enclosed in a 

 common membrane. 



SPORE (o-TTopa, a seed). Sporule. 

 The reproductive body in cryptogamic 

 plants, analogous to the seed of other 

 plants, but differing from this in its 

 mode of development and in its struc- 

 ture ; being produced apparently without 

 the agency of sexes, and not germinating 

 from any fixed point, but producing its 

 stem and root indifferently from any 

 points of its surface. 



SPORI'DIA. Granules resembling 

 sporules, occurring in algaceous plants, 

 but of doubtful nature. In fungaceous 

 plants, the term denotes the immediate 

 covering of sporules. Sporidiola are the 

 sporules themselves. 



SPRING. A piece of mechanism, 

 formed of a plate of steel or other elastic 

 substance, employed as a moving power, 

 or as a regulator of the motions of wheel- 

 work ; also for the purposes of producing 

 resistance, or of preventing a shock from 

 the collision of hard bodies. In the form 

 of the balance, it is employed as a means 

 of measuring weight or force. 



SPUR. Calcar. The name given to 

 a petal which is lengthened at the base 

 into a hollow tube, as in orchis, &c. 

 This is sometimes called nectarotheca, 

 though frequently without reason. 



SQUA'LID^. A family of chondro- 

 pterygious fishes, named from the genus 

 squalus, and including the various spe- 

 cies of sharks. 



SQUAMA. A scale; a term applied 

 in botany to any kind of hract which has 

 a scaly appearance. A diminutive of this 

 is squamula, and is used to denote each 

 of the minute hypogynous scales or 

 bracts found within the outer envelopes 

 of grasses. 



SQUA'MIPENNES {squama, a scale, 

 penna, a fin). A family of acanthoptery- 

 gious or spiny -finned fishes, in which 

 the soft and even the spinous parts of 

 their dorsal fins are covered with scales, 

 as well as the rest of their body. The 

 chaetodon may be taken as a type of the 

 family. 



SQUARE. In Geometry, a square is 

 a plane four-sided figure, with all its 

 sides equal, and all its angles right; or it 

 may be described as a rectangle, which 

 has two adjoining sides equal. In 

 • arithmetic and algebra, a square signi- 

 313 



fies the number produced by multiplying 

 a number by itself. The reason of this 

 double use of the word ' square ' is ob- 

 vious : the square of 12 is 144, and this 

 is the arithmetical mode of finding the 

 content of a square of 12 units in length 

 and breadth ; but, to avoid the confusion 

 occasioned by this double use of the 

 word, it has been proposed to speak of 

 the square on a line in geometry, and 

 of the square of a number in arithmetic 

 and algebra. See Power of Numbers. 



SQUARE MEASURES. Measures 

 of Superficies. In square measure the 

 yard is divided, as in general measure, 

 into feet and inches, 144 square inches 

 being equal to a square foot, and 9 square 

 feet to a square yard. For land measure, 

 the multiples of the yard are the pole, 

 the rood, and the acre; the pole being 

 equal to 30j square yards, the rood to 

 40 poles, the acre to 4 roods. 



SQUARE NUMBER ; SQUARE 

 ROOT. A square number is the product 

 of a number multiplied by itself, as 25, 

 the square of 5. A square root is the name 

 of a number with reference to its square, 

 as 5, the square root of 25. "When a num- 

 ber has no exact root, an approximate 

 root may be found by the usual process 

 of extraction : thus, 2 has no square root, 

 but 1.4142136 multiplied by itself, is 

 nearly 2, and is therefore the square root 

 of something very near 2. 



SQUARROSE. A term applied, in de- 

 scriptive botany, to parts which are 

 spread out at right angles from a com- 

 mon axis, as the leaves of some mosses, 

 the involucra of some compositae, &c. 

 By squarrose-slashed, as applied to leaves, 

 is meant, slashed with minor divisions 

 at right angles with the other divisions. 



STABLE and UNSTABLE. These 

 are terms employed in physics in 

 connexion with equilibrium and centre 

 of gravity. Suppose a body to be in equi- 

 librium under the action of any forces ; 

 let the body be arbitrarily displaced very 

 slightly from the position of equilibrium, 

 then if the forces be such that they tend 

 to bring the body back to its position of 

 equilibrium, the position is stable ; but if 

 they tend to move the body still further 

 from the position of equilibrium, it is 

 unstable. An egg will rest upon its side 

 in a position of stable equilibrium; if 

 placed on one end, it will be in a position 

 of unstable equilibrium. 



STAFF A. A small island, lying west 

 of the larger trap masses of Mull, en- 

 tirely composed of amorphous and pil- 



