THE 



[ 871 ] 



THI 



States. lu its scale, the freezing point 

 is ; and the boiling point, 80. On 

 Celsius or the Centigrade thermometer, 

 now used throughout France, and in 

 the northern kingdoms of Europe, the 

 freezing point is 0- ; and the boiling 

 point, 100. Hence, to reduce degrees 

 of temperature of the Centigrade ther- 

 mometer and of that of Reaumur to 

 degrees of Fahrenheit's scale, and con- 

 versely : 



Rule 1. Multiply the Centigrade de- 

 grees by 9, and divide the product by 

 ; or multiply the degrees of Eeaumur 

 by y, and divide by 4 ; then add 82 to 

 the quotient in either case, and the sum 

 is the degrees of temperature of Fahren- 

 heit's scale. 



Rule ^J. From the number of degrees 

 on Fahrenheit's scale, subtract -32; 

 multiply the remainder by o, for Cen- 

 tigrade degrees, or by 4 for those of 

 Reaumur's scale, and the product, in 

 either case, being divided by 9, will 

 give the temperature required, accord- 

 ing to Fahrenheit's. 



To ascertain the internal temperature 

 of a hothouse, the thermometer should 

 be fixed near its centre, against a 

 pillar, and under a cupola, or little roof, 

 shading it from the sun. 



A self-registering thermometer should 

 be in every house, for it shows the 

 highest and lowest degrees of heat 

 which have occurred in the twenty-four 

 hours ; and, therefore, serves 

 as a check upon those to whose 5\^ 

 care they are entrusted. 



Brega/zi's bark-bed ther- 

 mometer is an excellent in- 

 strument for ascertaining the 

 bottom-heat of hotbeds, bark- 

 pits, &c. It is a thermometer 

 inclosed in a metal tube, per- 

 forated to admit the heat, 

 pointed so as to be easily 

 thrust down, and with a small 

 door in the side, for observing 

 the degree of temperature \y 

 shown by the scale. 



THEKMO'PSIS. (From thermos, a Lu- 

 pine, and opsis, like; Lupine-like shrub. 

 Nat. ord., Leguminous Plants [Faba- 

 cea. 1 ]. Linn., 10 - Decaudria 1-JWewo- 

 yynia. Allied to Piptanthus.) 



Hardy, herbaceous, yellow-flowered peren- 



nials. Chiefly by seeds, sown in April ; light, 

 sandy loam. 



T. corgone'nsis (.Corgon). J. July. Altaia. 1820. 

 faba'cea (Bean -like). 2. June. North 

 America. 1811. 



lanceola'ta (spear- head-/eae0. 1. June. 



Siberia. 1779- 



THESPE 'SIA. (From thespesios, divine ; 



one of the trees often planted round 



i places of worship in India. Nat. ord., 



Mallow-worts [Malvaceae]. Linn., 10- 



Monadelphia $-PoIyandria.} 



Stove evergreen trees. Cuttings of stubby 

 side-shoots, in sand, in May, under a bell-glass, 

 in bottom-heat ; nbry, sandy loam, and a little 

 leaf mould. Winter temp., ,46 to 55; sum- 

 mer, 65 to 85, 



T. grandiflo'ra (large-flowered). 30. Scarlet. 

 Point Rico. 1837- 



popu'lnea (Poplar- leaved], 30. White. 



East Indies. 1/70. 

 Guadalupe'nsis (Guadaloupe). 30. 



Guadaloupe. 



THIBATJ'DIA. (Named after Thicbant. 

 de Uerneaud, a French botanist. Nat. 

 ord., Whortleberries [Vacciniacece ] . 

 Linn., S-Octandria l-Monoyynia.') 



Stove evergreens. Cuttings of half -ripe 

 shoots, in sand, under a bell-glass, and in 

 moist heat; sandy loam and fibry peat. Winter 

 temp., 50 to 60 ; summer, 60 to 85. 

 T. mucra'ntha (large-flowered). White, yellow, 



red. December. Moulmein. 1849- 



macropfty'lla (large-leaved). White. East 



Indies. 

 I microphy'lla (small-leaved). 2. September. 



Peru. 1847. 

 ! pulche'rrima (beautiful). 10. Red, green. 



May. India. 1845. 

 j __ _j gla'bra (smooth). C. Deep 



rose. September. Columbia. 

 i seti'geru (bristly). Scarlet. Khoosea. 1337. 

 i - vttccina'cea (Cranberry -like). Khoosea. 1837. 

 ' variega'ta (variegated). Scarlet. Khoosea. 



1837. 



THINNING. The exhaustion conse 

 i quent upon the production of seed is 

 I a chief cause of the decay of plants. 

 : This explains why fruit trees are weak- 

 ' ened or rendered temporarily unpro- 

 ductive, and even killed, by being al- 

 lowed to ripen too large a crop of fruit, 

 or to " overbear themselves." 



The thinning of fruit is consequently 

 one of the most important operations of 

 the garden, though one of the least 

 generally practised. It is equally im- 

 portant to be attended to in all fruit- 

 ! bearers, but especially the vine, uecta- 

 | rine, peach, apricot, apple, and pear. 

 It should be done with a bold, fearless 

 i hand ; and the perfection of that \vhHi 



