S P E 



S P E 



ters, by means of which the thing becomes a different fpe- 

 cies ; thefe are invariable, and by thefe names the thing is, 

 in fome fort, defcribed. The falfe ones are thofe fpecific 

 names which do not, and cannot di(lingui(h the fpecies 

 called by them from the others of the fame genus, which 

 may as well belong to fome other fpecies as to that, and 

 which therefore are of no ufe to the lludent. The true 

 formation of thefe names is on the real characters of the 

 body to be named ; but iiiftead of this, thefe falfe ones are 

 often formed from accidental or variable diftinftions. 



Specific Waters. See Water. 



SPECIFICATION, a term expreffing the engineer's 

 ttatement of the particulars of width, depth, flopes, &c. 

 which a certain length of canal is to have, when the exca- 

 vation is to be made by contraft. 



Specification is likewife a term ufed in obtaining pa- 

 tents. See Patent. 



SPECILLUM, a probe, one of the moll common in- 

 ftruments of furgery. See Surgical Plates. 



SPECIOUS Arithmetic. See Arithmetic. 



SFECKHAVEN, in Geography, a harbour on the W. 

 coaft of Weft Greenland. N. lat. 64°. W. long. 49° 40'. 



SPECKLED Beans, in Agriculture, a term applied to 

 fome forts of the kidney-bean, which are occafioiially cul- 

 tivated in the field, in fome diftridts. The principal va- 

 rieties which are grown and cultivated in this way in fome 

 parts of the county of Kent, are the black fpeckled and the 

 red fpeckled ; but many others may be employed for the 

 tame purpofe. 



The tillage preparation of the land for field-crops of this 

 fort's the fame as that which is made ufe of for the growth 

 of the common pea and bean ; and the manure, which is 

 >.ommonly ploughed in before the feed is put into the ground, 

 i', of the more rotten dung kind. See Pbas and Beans. 



The time of planting crops of this nature in the field is 

 m the early part of the fpring, as from about the eighth to 

 tiie twentieth of May, as when it is done earlier, the crops 

 are in danger of being injured, or wholly dellroyed, by the 

 occurrence of a frolly morning, which is then liable to take 

 place. 



In fetting, the feed-beans are dropped by the hand into 

 holes, or fmall furrows or drills made for the purpofe m the 

 land, in the quantity of from five to ten gallons to the acre, 

 in proportion to the fize of the fort which is employed ; 

 the fmaller the fort of bean, the lefs the quantity which is 

 neceflary. 



The crops are repeatedly hoed while growing, fo as to be 

 kept perfedtly clean and free from weeds of all kinds ; and 

 in their more early growth the fine moulil is a little drawn 

 up to the rows, in order to promote the advancing of the 

 young plants. 



The harvciling of the crops is by pulling up the 

 plants by the roots, as the beams become ripe, dunng the 

 beginning of the autumnal fcalon. The more early forts 

 are comn:only ready and fit to be pulled about tlic end of 

 Augull ; but the late ones are often not ripe and ready for 

 pulhiig until the month of Oftobcr. Thofe which ripen fo 

 late in the feafon, and arc in danger of being injured by 

 v;ct weather, are frequently tied up in fmall bunches, and 

 hung upon poles to finidl their ripening, and, when 

 thoroughly dry, are threlhcd out and fcnt to market, as 

 they IcTdom keep well. 



Thele forts of bean-crops arc much cultivated and at- 

 tended to about the town of Sandwich, and in the Ifie of 

 Thanet, in the fame county, as well, perhaps, as in fome 

 other fouthcrn parts of the ifland, for the purpofe of fup- 



10 



plying the London feedfmen with thefe kinds of beans. See 

 Phaseolus. 



This is a profitable fort of culture in fome cafes and fea- 

 fons, but liable to much uncertamty. 



SPECTABILES, among the Romans, a title of honour 

 given to the fecond rank, or degree of nobility, under the 

 Roman emperors, being unknown in the time of the re- 

 public. There were two other degrees ; the firll had the 

 title of illuftres, and the third that of clarij/lmi. 



SPECTACLE, Spectaculum, Show ; fome extraor- 

 dinary objeft, which draws the view and attention ; and is 

 not beheld without fome emotion or palTion of the mind. 



The term is chiefly ufed, by the ancients, for theatrical 

 and amphitheatrical performances ; for comedies, combats 

 of gladiators, and of beafts ; and even for folemn proceflions, 

 as thofe of the Circus, &c. 



The people of Rome were extremely fond of fpeftaoles ; 

 and the Roman hiftorians obferve, that there was no furer 

 way of gaining their affeftions, and making parties to in- 

 troduce tyranny and oppreflion, than by the ufe of fpec- 

 tacles. 



SPECTACLES, an optic machine, confiding of two 

 lenfes fet in a frame, and applied on the rofe, to affilt in 

 defeftsof the organ of fight. 



It is well known, that parallel rays, or fuch rays as pro- 

 ceed from a very diftant luminous point, will be coUefted, 

 by the refraftions of all the humours through which they 

 mutt pafs in the eye, to a focus on the retina, which is the 

 true place of the image. But at the fame time it is evident, 

 that if that be the focal diftance for parallel rays, it cannot 

 be the focal dittance for diverging rays ; or, in other words, 

 when the objects are fituated at a few feet dillance from the 

 eye, their true images muit be formed farther back ; con- 

 fequeiitly their miages upon the retina mult be imperfeft, 

 unlefs the retina be fituated farther back by an elongation 

 of the axis of the eye, or the focal diftance be (liortentd 

 by the alteration of fome other part. But fince we may 

 perceive either diftant or near objefts diftindly, it is evident 

 that fome fuch alteration does adtually and necefiarily take 

 place. This is called the adjuftmcnt, or accommodation of 

 the eye fordillintt vifion ; but the difficulty is to determine 

 how this adjuftmcnt is effefted. 



By fome perfons it has been attributed to a change in the 

 length of the eye, and by others to a change of curvature 

 in the cornea ; but fome very recent experiments render 

 thofe alterations unlikely, at leaft to the full amount of 

 what may be required. Other ingenious perfons have 

 attributed the alteration to a change either of the fiiape of 

 the cryftaUine lens, or of its fitnatii^n, or of both ; and this 

 opinion feems upon the whole to be nearer the truth. 



That the eye cannot fee both near and remote objedls 

 diltindtly at the fame lime, may be cafily proved. Let a 

 tree, a houfe, or fome other objeft, be upwards of fifty 

 feet from you ; (hut one eye, and whilft you are looking 

 uith a fingle eye at the tree, &c. hold a pin, a pencil, or 

 fome other objeit, in the fame direftion, at about a foot 

 diftance from tlie eye ; and it will be found, that whilft 

 you fee the pin diftindtly, the tree will appe.ir indiftiiift ; 

 but if you adjnft your eye fo as to lee the tree dilliiiAly, 

 then the pin will appear indiftinft. 



The eyes of fome perfons arc more capable i,f adjuft- 

 mcnt than thofe of others. In old perfons the humours 

 grow tliickcr, and the parts lefs pliable ; hence their cye;i 

 are lefs capable of adjuftmcnt than thofe of young perfons. 



The eyes of lome perfons can be adjufted for diftant 

 cbjeds better than for near objeft?, and vice verfa. When 



the 



