Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/924

 S T A

holding things ; that they have only two eyes, and that the

tail is foliated.

The fquilla may be conveniently arranged under three fub-

divifions. I. The fmaller long-tailed fquilla, commonly

■called fhrimps. 2. The larger long-tailed fquilla, or the

hbftcr and cray-fifh kind. 3. The ihort-tailed kind, called

alio canceres, and in Englifh crabs.

Of thofe denominated primps we have the following fpecies.

I. The long-tailed fquilla, with the fnout ferrated above, and tridentated below. This is the common primp. 2. The long-tailed fquilla, with a fmooth fnout, called the fmooth- nCski Jhrimp. 3. The long-tailed fquilla, with a foft tail, and the ri^ht claw largeft. This is called the hermit. 4. The larger, long-fnouted kd.-fquilla. 5. The fmaller, narrow- fnouted fea- fquilla. 6. The frefh-water fmall fquilla.

Gf the fecond order of fquilla, commonly called lobjlers, or cray-fifh, we have the following fpecies. I. The common

■■•' labfter. 2. The thick-horned, llender-bodied labfter. 3. The fhort and broad-bodied labfter. 4. The very long-bodied labfter. 5. The fmall-bodied kbjler. 6. The great fea tray-fijh. 7. The cray-jijb with the fnout ferrated above, and with a fingle denticulation at the bafe. This laft fpe- cies, -though only three inches and an half in length, greatly approaches to the figure of the common labfter. Of thofe fquilla:, called crabs, ccmctres, there are the follow-

■ ing fpecies. 1. The common large crab. 2. The wart- crab, cancer verrucous. 3. The fpiier-crab, or long-legged, (hort-tailed fquilla. 4. The king-crab, or molucca-crab, call- ed thefquilla c/ypeata. 5. The rough-bodied, fmooth-clawcd fquilla, called cancer mceas. 6. The fmooth and long-clawed crab, called by Johnfton the female of the common kind. 7, The little fquall crab. 8. The little woolly crab. 9. The thick-bodied duck crab. 10. The round-bodied duck crab.

II. The common, or oval-bodied duck era*. 12. The very long-armed duck crab. 13. The very fmall-bodied, rough, long-armed crab. 14. The lunar crab. 1 5. The florid crab. 16. The frog crab. 17. The prickly and hairy, long-armed crab. 18. The great prickly, long-armed crab. 19. The fhort-bodied, reticulated crab. 20. The elliptic-bodied crab. 21. The fmooth, long-legged crab. Vid. Hill, Hift. Anim. p. 28, fcq. and Table of Cruftaceous Animals, N' 18, 19, csV.

Sojiil, fcilla, in botany, the Englifh name of a difiintt genus of plants. See the article Scilla, Append.

Squill, fcilla, in botany, the Englifh name of a diftinct genus of plants, according to Linnaeus ; but comprehended under the ornitbogala by Tournefort. See the article Ornitho-

GALUM, Sltppl.

STAFF (Suppl.)— Shepherd's Staff, or Jliepberd's red, in bo- • " tany, the name of a genus of plants, called by botanifts clipfacus. See the article Difsacus, Suppl.

STAG-beetle, in the hiflory of infeas, the Englifh name of a fpecies of fcarabaus, with ramofe horns. See the article Scarabjeus, Suppl.

Stag's horn-tree, a name fomctimes given to the rhusj or fumach, a dilUnS genus of plants. See the article Rhus, Suppl.

STAGGARD, among fportfmen, a young male deer only four years old. Ruff. Diet, in voc.

STAINING (Suppl.)— Staining of ham. See the article Horn, Append.

Staining of ivory. See Ivory, Append.

STANDARD (Suppl.) — Standards, in fbip-building, a fort of knees fayed from the deck to the .fides of the fllip within board, to ftrengthen her. Blmdley, Naval Expofi- tor, in voc

STAPHYL/EA, in the Linnaean fyftem of botany, the name of a genus of plants, called by Tournefort Jlaphylodendron. See thearticle Staphvlodendron, Suppl.

STAPHYLINUS, in zoology, the name of a genus of four- winged flies, the antenna? of which are flender and filiform. There are two veficles fituated above the tail. The exte- rior wings are dimidiated and fhort.

Of this genus there are a great many fpecies, diftinguifhed from each other by the colour of the fevera! parts of their bodies. Vid. Hill, Hift. Anim. p. 57.

STAR (Suppl.)— Our excellent aftronomer, Dr. Bradley, had no fooner difcovered the caufe, and fettled the laws of the aberration of the fixed Jlars b, than his attention was again excited' by another new phenomenon, viz. an annual change of declination in fume of the fixed Jlars, which appeared to be fenfibly greater than a proceflion of the equinoctial points of §o' ; in a year, the mean quantity now ufually allowed by aftronomers, would have occafioned. — [ b See the article Light, Append]

This apparent change of declination was obferved in the Jlars near the equinoctial colure ; and there appearing at the fame time an effect of a quite contrary nature, in (ome Jlars near the foiftitial colure, which feemed to alter their declination Jefs than a proceflion of 50" required, Dr. Bradley was thereby convinced, that all the phacnomena in the different Jlars could not be accounted for merely by fuppofing that he had affumed a wrong quantity for the proccilion of the oquinocfial points. He had alfo, after many trials, fufficient

S T A

reafon to conclude, that thefe fecond unexpected deviations of the Jlars were not owing to any imperfection of ; his in- ftruments. At length, from repeated obfervations, he be- gan to guefs at the real caufe of thefe phenomena. It appeared from the Doctor's obfervations, during his resi- dence at Wanned, that fome of the Jlars near the foiftitial colure had. changed their declinations 9" or 10" le(s than a proceflion of 50" would have produced ; and, at the fame time, that others near the equinoctial colure had altered theirs about the fame quantity more, than a like preceffion would have occafioned : the north pole of the equator feem- ino- to have approached the Jiars, which come to the me- ridian with the fun, about the vernal equinox and the winter folftice ; and to have receded from thofe, which come to the meridian with the fun, about the autumnal equinox and the fummer folftice.

From the confideration of thefe circumftances, and the fi- tuation of the afcending node of the moon's orbit when, he firil began to make his obfervations, he fufpedicd that the moon's action upon the equatorial parts of the earth might produce thefe effects. For, if the precefhon of the equinox be, according to Sir Ifaac Newton's principles, caufed by the actions of the fun and moon upon thofe parts ; the plane of the moon's orbit being, at one time, above ten degrees more inclined to the plane of the equator, than at another; it was reafonable to conclude, that the part of the whole an- nual preceflion, which arifes from her action, would in dif- ferent years be varied in its quantity ; whereas the plane of the ecliptic, wherein the fun appears, keeping always nearly the fame inclination to the equator, that part of the preceffion, which is owing to the fun's action, may be the fame every year ; and from hence it would follow, that although the mean annual preceflion, proceeding from the joint actions of the fun and moon, were 5°"» vct the ap- parent annual preceflion might fomctimes exceed, and fome- times fall fhort of that mean quantity, according to the va- rious fituations of the nodes of the moon's orbit. In the year 1727, the moon's afcending node was near -the beginning of Aries, and confequently her orbit was as much inclined to the equator, as it can at any time be ; and then the apparent annual preceflion was found, by the Doctor's firft year's obfervations, to be greater than the mean ; which proved, that the Jiars near the equinoctial colure, whofe declinations are moft of all affected by the preceflion, had changed theirs, above a tenth part more than a preceffion of 50" would have caufed. The fucceeding year's obferva- tions proved the fame thing ; and in three or four years time the difference became Co confiderable, as to leave no room to fufpect that it was owing to any imperfection either of the inftrument, or obfervations.

But fome of the Jiars, that were near the foiftitial. colure, having appeared to move, during the fame time, in a man- ner contrary, to what they ought to have done, by an increafe of the preceftions ; and the deviations in them being as re- markable as in the others, it was evident that fomething more than a mere change in the quantity of the preceffion would be requifite to folve this part of the phenomenon. Upon comparing the obfervations of Jiars near the foiftitial colure, that were almoft oppofite to each other in right af- cenfion, they were found to be equally affected by this caufe. For whilft y Draconis appeared to have moved northward, the fmall Jlar, which is the 35th Camelopardali Hevelii,. in the Britifh. catalogue, feemed to have gone as much towards the fouth j which fhewed, that this apparent motion in both thofe Jiars might proceed from a nutation in the earth's axis ; whereas the comparifon of the Doctor's obfervations of the fame Jiars, formerly enabled him to draw a different conclufion, with refpect to the caufe of the annual aberra- tions ar-ifmg from the motion of light. For the apparental- terati'on in y Draconis, from that caufe, being as great again as in the other fmaller, proved, that that did not proceed from a nutation of the, earth's axis; as, on., the contrary, this may. Upon making the like comparifon between, the obfervations of other Jiars, that lie nearly oppofite in right afcenfion, whatever their fituations were with refpect to the cardinal points of the equator, it appeared, that their change of declination was nearly equal, but contrary ; and fuch as a nutation or motion of :tbe earth's axis would .effect. The moon's afcending node being got back towards the beginning of Capricorn in the year 1732, the Jlars near the equinoctial colure appeared about that time to change their declinations no more than a preceflion of 50" required ; whilft fome of thofe near the foliiitial colure altered theirs above 2" in a year lefs than they ought. Soon after the an- nual change of declination of the former was perceived to be diminifhed, fo as to become lefs than what 50" of pre- ceflion would caufe; and it continued to dimihiih till the year 1736, when the moon's afcending node was about the beginning of Libra, and her orbit had the leaft inclination to the equator. But by this time, fome 0/ the Jiars near the foiftitial colure had altered their declinations 18" lefs, fmce the year 1727, than they ought to have done from a preceffion of 5c". For y Draconis, which in thofe nine years fhould have gone about 8" more foutherly, was obferved 2 in