TOP 



in fome cafes, fliould, as in the other duft-top-dreffings, be 

 made ufe of in as dry a condition as pofllble, and without 

 undergoing any degree of fermentation. It is ufed in the 

 firft of the above counties for wheat, in nearly the fame 

 quantities as other fuch matters, in fome places, at the rate 

 of twelve (hillings the quarter ; and it works much the beft, 

 it is faid, on lands that are inclined to be rather wet. See 

 GRASs-Z-fl«i/, Gypsum, Salt, &c. 



Top-dreffings of thefe kinds are often well fuited to and 

 admirably beneficial for recovering and reftoring backward 

 and ftunted crops of different forts, but particularly thofe 

 of the grain and grafs kinds. 



Top-FoUwg, a term applied to the praftice of feeding 

 down fome forts of fpring corn-crops with (beep, as thofe 

 of the wheat, and occafionally the barley kinds, when too 

 rank or luxuriant. It is a method of praftice which is 

 much in ufe in fome parts of Hertfordftiire, and which is 

 faid there to be very beneficial in its effefts ; it (hould, how- 

 ever, be employed with caution in moft cafes, and conftantly 

 in the early dates of growth of the grain, as in the more 

 advanced ones it muft always be hazardous, and often hurt- 

 ful and deftruftive of fuch crops. The feeding down in 

 thefe cafes muft, of courfe, be nicely regulated, fo as never 

 fo fuffer the crops to be too much or too little e;aten by the 

 (heep, as in either extreme the confequences will be injurious 

 to them. 



Top-Up, a term ufed to fignify the making up or topping 

 the roofs of hay or corn-ftacks or ricks. It is likewife 

 fometimes made ufe of, in feeding and fattening bullocks, 

 to imply full feeding, or to finifh highly, as with cake, 

 oats, &c. 



Top-Wood, in Rural Economy, the boughs or branches 

 which form the tops of timber, or other trees, or the wood 

 which they contain. See Timber and Trees. 



TOPAN, in Ornithology, a name by which fome have 

 called the horned-beaked Indian raven, more ufually known 

 by the name of the rhinoceros-avis. 



TOPARCHY, formed from tob-o,-, place, and a^x^, go- 

 •vernmenl, a little ftate, or fignory ; confifting only of a few 

 cities, or towns ; or a petty country, governed and poflefled 

 by a toparch, or lord. 



Judxa was anciently divided into ten toparchies. See 

 Pliny, lib. v. cap. 14. and Jofeph. lib. iii. cap. 2. de Bel. 

 Jud. & lib. V. &c. 



Procopius only gives the quality of toparchy to the king, 

 dom of Edefla ; to Abgarus, the toparch or lord of which, 

 tliere is a tradition, that Jefus Chrift fent his pidlure, with 

 a letter. 



TOPAYOS, in Geography, a river of Brafil, which runs 

 into the river Amazon, with a fort at its mouth of the fame 

 name. S. lat. 2° 30'. W. long. 57° 6'. 



ToPAYOS, a favage tribe in Brazil, the chief and moft 

 numerous of the kind. They are anthropophagi ; and if 

 a woman mifcarry, will greedily devour the fostus. Strangers 

 to cultivation, they live upon fruits, and the animals they 

 kill. The Topayan language is very widely diffufed, and is 

 divided into feveral dialefts. Their nakednefs, ferocity, 

 vindi£live fpirit, war cries, and whole mode of exiftence, 

 have been particularly defcribed by Lery. 



TOPAZ, in Mineralogy, a gem fo called from Topazos, 

 a fmall ifland in the Red fea, where the Romans formerly 

 obtained a ftone called by them the topaz, but which is the 

 chryfolite of the moderns. The topaz is faid to have been 

 firft found by Juba, king of Mauritania ; but it was known 

 to the Hebrews before, as appears from the 11 8th Pfalm. 

 The moft valued topazes are thofe of Saxony, Siberia, and 

 Brazil. 

 Vol, XXXVI. 



TOP 



The principal colour of the topaz inclines to yellow, 

 called by profeflbr Jamefon wine-yellow. The pale wine- 

 yellow pafles from various (hades of yellowifti and greenifti- 

 white to green. The dark vtine-yellow pafli^s from orange 

 to cherry -red and even to blue, but the latter colour is very 

 rare. The topaz fometimes occurs maflive and in rolled 

 pieces, but more frequently cryftalhzed. The cryftals are 

 feldom very large. The primitive form of the cryftal, ac- 

 cording to Haiiy, is a reaangular oaahedron. The com- 

 mon forms of the fecondary cryilals are varieties of the 

 oblique four-fided prifm, terminated by four planes. The 

 fides of the prifm are longitudinally ftreaked, but the termi- 

 nating planes are fmooth. When the edges of the cryftals 

 are truncated, the truncated planes are alfo fmooth. The 

 Brafilian and Siberian topazes are more deeply ftreaked than 

 the Saxon. The external luftre of the topaz is fplendent, 

 the internal vitreous. The longitudinal frafture is fmall, and 

 imperfeftly conchoidal ; the crofs frafture is ftraight, and 

 exhibits a lamellar ftrufture. The topaz is tranflucent or 

 tranfparent, and refrafts double : it fcratches glafs, but is 

 fcratched by fpinel : it is eafily frangible. The fpecific 

 gravity varies from 3.464 to 3.641. 



The Saxon topaz becomes colourlefs by a gentle heat, 

 and in this ftate is fometimes fold for the diamond. A 

 ftrong heat deprives it of its luftre and tranfparency. The 

 Brafilian topaz, by expofure to a ftrong heat, becomes red ; 

 and in a ftill higher temperature, violet-blue ; it is then 

 fometimes fold for the ruby, or for pale fpinel. The topaz 

 is infufible by the blowpipe, but melts with the addition of 

 borax. The topazes of Brazil, Siberia, and Afia Minor, 

 become eledtrical by heating. The conftituent parts of this 

 gem appear to vary confiderably in different fpecimens. 



The topaz is found in various parts of Europe and Afia, 

 and in South America. It occurs in large quantities in a 

 rock denominated by Werner the topaz rock, which is an 

 ^gS'^^S^^^ °f maflive topaz, quartz, and fchorl, in which 

 there are frequently fmall cavities lined with cryftals of 

 thefe three fubftances, and portions of lithomarge. This 

 rock is fituated at Schneekenftein, in Saxony. 



It occurs alfo in veins of quartz at St. Michael's mount, 

 in Cornwall, and with tin-ftone at St. Anne's, in the fame 

 county. The topaz has recently been found, in large cryf- 

 tals and rolled pieces, in alluvial foil in the primitive countiy 

 of the upper part of Aberdeenfhire ; indeed it is ftated, 

 in the firft volume of the Wernerian Memoirs, that a fpeci- 

 men of topaz, weighing one pound three ounces eight drachms 

 troy weight, has been obtained from that part of Scotland. 

 The largeft fpecimen of Brafilian topaz in the mufeum of 

 natural hiftory at Paris, weighs four ounces two gros. In 

 this mufeum there is alfo a fuperb Indian Bacchus engraved 

 on topaz. Tavernier mentions a topaz, in the pofteiSon of 

 the great Mogul, weighing one hundred and fifty-feveu 

 carats, which coft 20,300/. fterling : and Boetius de Boot, 

 in his treatife of precious ftones, affirms to have feen in 

 the cabinet of the emperor Rudolphus, whofe phyfician he 

 was, a topaz above three feet long, and fix inches broad. 

 Probably, it might be fome other ftone a little tranfparent, 

 of a topaz colour. This gem was much prized by the 

 ancients. Yellow-coloured rock-cryftal has not been unfre- 

 quently impofed on the ignorant for topaz. 



The oriental topazes, which have a deep rich orange- 

 eolour, are highly valued at prefent. The Brafilian topaz 



F has 



