76 



GLOSSARY. 



floor or area). A circle apparently 

 round the sun or moon, sometimes 

 white and sometimes coloured, pro- 

 duced by the passage of light 

 through or near vapours in the 

 atmosphere. 



Hal'ogen (Gr. a\s, hals, salt ; yevvaca, 

 genna'o, I produce). Producing 

 salts by combination with metals. 



Haloid (Gr. oAs, hols, salt; eloos, 

 eidos, form). Resembling salt : a 

 name given to a class of saline sub- 

 stances constituted of a metal, and 

 another element which is a salt 

 radical ; after the type of common 

 salt or chloride of sodium, where 

 sodium is the metal, and chlorine 

 the salt radical or halogen. 



Ham'ite (Lat. hamus, a hook). A 

 genus of fossil shells of cephalopoda, 

 with a hook at the e.:d. 



Hanno'nia (Grr. ap/mofa, harmozo, I fit 

 together). A form of articulation in 

 which the surfaces of bones are 

 merely placed in apposition to each 

 other, so as not to allow motion. 



Harmon'ical (Gr. apjuoco, harmozo, I 

 fit together) . Relating to harmony ; , 

 concordant. 



Hririnonical Proportion. In arith- 

 metic, that relation of four quanti- 

 ties to each other, in which the 

 first is to the fourth as the difference 

 between the first and second is to 

 the difference between the third and 

 fourth. 



Har'mony (Gr. ap/j.ofy, harmozo, I fit 

 together). A proper fitting of parts 

 together ; agreement ; in music, the 

 effect produced on the ear by the 

 sounding of notes, the vibrations of 

 which have a certain limit of co- 

 incidence. 



Has'tate (Lat. hasta, a spear). Like 

 a spear. 



Haustellate (Lat. haustd'lum, a 

 sucker). Having a sucker for 

 sucking or pumping up fluids ; ap- 

 plied to a large division of insects. 



Haustel'lum (Lat. hau'rio, I draw). 

 A sucker, such as some insects are 

 provided with for taking their 

 liquid food. 



Haver'sian Canals (Havers, a physi- 

 cian, their discoverer). Small longi- 



tudinal canals in the substance of 

 bone. 



Heat. The sensation produced by 

 the contact of a hot body; the 

 quality of the body by which this 

 sensation is produced ; caloric, or 

 the agent to which the quality is 

 due. Sensible heat is that which 

 is perceptible to the body. Latent 

 heat is that which a substance re- 

 ceives or loses without exciting an 

 increased or diminished sense of 

 warmth. Specific heat is the amount 

 required to raise a substance to a 

 given degree of temperature. 



Hebdom'adal (Gr. eySSojitas, heb'domas, 

 a period of seven days). Relating 

 to a week. 



Hectic (Gr. e<y, hex is, habit). A form 

 of fever arising from local irritation 

 in a weakened constitution. 



Hec'togramme (Gr. l/caroi/, hek'aton, 

 ahundred; FT. yramme). A French 

 weight of 100 grammes, or about 

 3^ pounds avoirdupois. 



Hec'tolitre (Gr. J/carov, hek'aton, a 

 hundred ; Fr. litre, a quart). A 

 French measure of 100 litres. 



Hec'tometre (Gr. knarov, hek'aton, a 

 hundred ; Fr. metre). A French 

 measure of 100 metres, or about 

 328 British feet. 



Heli'acal (Gr. rj\ios, helios, the sun). 

 Emerging from, or passing into the 

 light of the sun. 



Helianthoi'da (Gr. rj\ios, helios, the 

 sun ; avdos, anthos, a flower ; ciSos, 

 eidos, shape). An order of polypes, 

 resembling a sun-flower in appear- 

 ance ; of which the actinia or sea- 

 anemone is an example. 



Hel'icoid (Gr. e\<|, helix, a spiral 

 body ; ei'5os, eidos, shape). Twisted 

 like the shell of a snail. 



Hel'ical (Gr. eA,, helix, a spiral 

 body). Spiral. 



Helicotre'ma (Gr. e\i, helix, a spiral; 

 r/JTjjua, trema, a hole). An opening 

 in the apex of the cochlea, or spiral 

 structure of the internal ear. 



Heliocen'tric (Gr. f)\ios, helios, the 

 sun; Ktvrpov, kentron, a centre). 

 Having relation to the centre of 

 the sun. 



Heliocen'tric Lon'gitude. The angle 



