REFRACTION, REFRANGIBILITY. 



REFRIGERATION OF THE GLOBE. 



I cent to friends. About 900 boys luva been sent out M emigrant* 

 to Canada, the United States, and Australia, sinew the commencement' 

 of the school. From a statement showing the d ; sposal of the bo; 1 

 during four years, 1855-1858, it would appear that about 11 per cent- 

 of the emigrant*, and about 28 per cant, of those in home employment*, 

 relapsed into crime. 



Much of the sueoess of the Philanthropic Society's operations is due 

 to the excellent management of the Rev. Sydney Turner, now govern- 

 ment inspector of reformatories, who was chaplain and secretary to the 

 institution for a number of years. 



The following reformatories are in operation in and near Brittol : 

 Kingswood (established 1852', for luu moles; Red Lodge (1854), for 

 60 girls; Arno's Court (Roman t'a'holic, 1858), for 300 females. The 

 LirtrpoLl Farm School, situated at Newton, near Warrington, with 

 accommodation for M. boys, was established in 1859. The magistrates 

 in Liverpool hav taken pains to apply the provisions of " The Youth- 

 ful Offenders AoU," and the results have been hii<bly satisfactory. In 

 the five yesrs preceding the passing of these Acts the average number 

 of juvenile offenders committed to prison was 1080 ; in the five years 

 following the average fell to 761 ; the highest number was 1148 

 in 1S52 ; the lowest 486 in 1858. The daily average of juveniles in 

 prison in 1854 was 110; in 1859 it was a 'fraction under 25. The 

 gangs of juvenile offenders which formerly infested and plundered the 

 town have been quite broken up. Parents have been called upon, in 

 accordance with the provisions of the Acts, to pay towards the expense 

 of thus reforming and training the children they have neglected, the 

 amount reaching, on an average, about 2507. a year. xeter had a 

 Fem.ale Kefuge for discharged prisoners of the Western Counties as 

 early as 1836. with accommodation for 20 inmates : it has now, in 

 addition, the Devon and Exeter Reformatory Farm School, at Bramp- 

 ford Wood, founded in 1855, for 80 boys, and the girls' reformatory for 

 the Western Counties, for 50 inmates, commenced in 1858. The 

 Castle Howard Reformatory, at Welburn, near York commenced in 

 1856. with accommodation for 80 boys, receives youths sentenced to 

 detention who have been previously once, or oftener, convicted, from 

 the North and Kast Ridings, the City of York, and the town of Hull. 

 The boys are employed chiefly in spade husbandry, and are much ;n 

 request as labourers by the farmers in th neighbourhood. The num- 

 ber of juvenile offenders in the North and East Ridings has greatly 

 diminished since the opening of the school. With respect to the town 

 of Hull, the testimony of the stipendiary magistrates in, that " juvenile 

 crime, as a system, is broken up." The Mane/utter and 

 Reformatory, at Blackley, has accommodation for 50 boys. At Bir- 

 mingham, the Saltley Reformatory Institution, Small Heath, has 

 accommodation for 100 boys ; and the Srnethwick Reformatory has 

 accommodation for 45 girls. At Wakejidd, the West Hiding Reforma- 

 tory School for girls wan commenced in 1856. 



REFRACTION, REFRANQ1BILITY. Refraction is the turning of 

 a ray of light, heat, or other imponderable substance from its direction, 

 when it falls obliquely on the surface of a medium differing in density 

 from that through which it had previously moved. The differently 

 coloured rays of light have different degrees of refrangibility, as evi- 

 denced by the common prismatic spectrum ; in other words, the re- 

 fractive indices of different lights vary for a given medium. The 

 fundamental law of refraction and the optical effects of this law are 

 discussed under the heads LIGHT and OPTICS, and a table of refractive 

 indices is given in the article OPTICS, PRACTICAL. For the different 

 refrangibihtiea of the rays, the articles DISPEHSIOH and Aom.< 

 may be consulted, and for one of the most striking phenomena thence' 

 arising see HAIXBOW. On the subjects of Fraunhofer's lines and of 

 double refraction, see DISPERSION and UKDULATORY THEORY. 



The doctrine of refraction, as distinguished from reflection, is called 

 dioptrics, and the caustics formed by the continued intersections of 

 refracted rays emanating from a luminous point, are termed dia- 

 oaustics ; properly speaking, these are surfaces, but by confining the 

 investigation to the plane of refraction, they are generally treated an 

 curves. A diacaustio curve, like a catacaustic, has the property of being 

 rectifiable. They are noticed in the articles above quoted, but they 

 are rather objects of analytical dexterity than of practical use. 



So long as the medium into which the refracted ray enters remains 

 of uniform density, the ray will pursue a straight course, but every 

 alteration of density in the medium gives rise to a corresponding 

 deviation in the path of the ray. Now the air is a medium of which 

 the density continually increases as its altitude above the surface of 

 the earth diminishes ; its density is also altered in the same stratum 

 by inequality of temperature, and frequently from the aqueous and 

 other vapours which it holds. Hence arise the ordinary terrestrial 

 refraction and the phenomena of Mirage, Fata Morgana, Ac., which are 

 treated under their respective heads. 



A ray of light proceeding from a star which is not vertical, on enter- 

 ing the atmosphere is bent towards the radius drawn from the earth's 

 caiitre to its point of incidence, and upon its successive incidences on 

 the lower strata it continues to band towards the successive radii, thus 

 describing a curvilinear trajectory through the air. The star is visible 

 in the direction of the tangent to this curve, at the point at which it 

 meets the e\ e of the spectator ; hence the apparent altitude of the 

 ston is increased by refraction, and thus the sun, moon, &c., are visible 

 before the real time of rising and after that of setting. 



From the causes above assigned for atmospheric refraction, it follows 

 that the nearer the direction of the ray is to the plan? of th h 

 he greater is it* refraction, and the refraction is nothing when the ray 

 s vertical. Thin is the cause of the apparently oval forms of the sun 

 and moon in the horizon ; for the sun s angular diameter being i 

 at 82 minutes, its lower limb is elevated through horizontal refr, 

 more than its upper by 4 minutes 64 seconds. 



Atmospheric refraction of the solar rays after sunset, combined with 

 subsequent reflect!' light 



thrown on the moon's surface when eclij > arth. 



The amount of refraction of rays proceeding from a celestial 

 would be proportional to the tangent of ir< zenith dint. 

 atmosphere were homogeneous, and the tance suffiY 



allow us to regard the refracting strata of air as boun.1 

 larallel surfaces. Not only, however, is the atmosphere <! 

 lomogeneity, but its state is continually altering, as shown 1 

 jarometer, thermometer, and hygrometer. A partly empiric tot 

 ;he result of numerous observations made by Bradley, gives a good 

 correction relative to the first two of these instruments, namely : 



Let r = 57'' x tang, zenith dist. (z) ; 



h = height of thermometer (Fahrenheit) ; 

 a = altitude of barometer in inches. 

 B = the required refraction ; then shall 



a 400 



B = 67 " 2p 350+A *> (* - 3r) nearly. 



Similar formulas have been the objects of analytical research to 

 Laplace and other modern mathematicians ; their results are however 

 not well adapted for insertion in this work. 



REFRACTION, DOUBLE. [Poi..\im.\TioN OF LIGHT ] 



REFRIGERANTS are remedial agents which directly diminish the 

 force of the circulation, and reduce the heat of the body or a portion 

 of it, without occasioning any diminution of the ordinary sensibii 

 nervous energy. This definition must not be considered as excluding 

 cold from among the number of such agents, , is capable, 



when carried to extremes, of rendering the sensibility null, and utterly 

 extinguishing the nervous power ; it is only its moderate and ' 

 political employment which is here contemplated. Cold, however, has 

 of late been recommended to be carried locally to an extreme degree, 

 utterly destroying for a time and special purpose the sensibility, thus 

 acting as an anaesthetic It is likewise applied to the spine with 

 benefit in some cases of tetanus. 



The manner in which refrigerants effect the ends which they n 

 plish is far from being understood: and a remarkable feature in 

 character is. that they display their peculiar effects chiefly win 

 action of the organs is above their natural standard, and more heat 

 than natural is evolved. Till we have a perfect knowledge of the 

 sources and mode of formation of animal heat, we are not likely to 

 possess a correct theory of their mode of operating ; and at present, what- 

 ever plausibility the mere chemical hypothesis of Dr. Murray exhibits, 

 we cannot consider the evolution of animal heat to be other than a 

 vital process. This function is mainly carried on in the capillai 

 extreme vessels, and is much influenced by the amount of supply of 

 nervous energy to these vessels. Hence, when a limb is [ 

 is colder than the opposite sound member; or when a sin. 

 injured, the parts supplied by it have a lower temperature th. 

 surrounding ones. Whatever, therefore, hinders the free communi- 

 cation of the nervous power to a part or to the whole .-y.-U'in, will 

 lessen it< quantum of animal heat. By applying to the surface of the 

 body any acid, the calibre of the capillaries is lessened, and hence the 

 paleness which is i .ing to less blood entering them. As the 



blood furnishes the pabulum from which the nerves evolve tin 

 the less fuel the vessels contain, the less potent will be th' 

 resulting. The introduction of any article of the class of refrigerants 

 into the stomach appears to operate by sympathy on the whole 

 vascular system, as may be eeen in the case of dilute sulphur;, 

 checking haemorrhage. The agents which are usually regarded as 

 refrigerants are weak vegetable acids, or very greatly diluted mineral 

 acids ; some saline, neutral, or super salts : and cool air. ice-cold water, 

 and externally evaporating lotions. An indirect refrigerant is found in 

 diminishing the quantity of animal food. [ANTIPHLOGISTIC THEAT- 

 MKNT; I'.ATIMXH: LOTIONS.] 



REFRIGERATION OF THE GLOBE. Since the mathei. 

 researches of Foui i ig the diffusion and conduction of heat 



in a mass constituted as the earth appears to be in thi 

 surface, have become in some degree known, geologists have been much 

 encouraged in .attempting to connect with a gradual chan^ 

 diminution of the internal temperature of the globe, such as 

 be consistent with Fourier's theoretical result her order of 



geological inferences. The ]>i 1 if not uni 



base of once melted rocks below all the strata, the peculiar 

 called metamorphic) condition of the lowest of mpared with 



the upper, the absence or rarity of fossils in the lowest stra 1 

 :.'0 of even general high surface temperatures on the ;i 

 land and in the ancient sea as contrasted with the modern distii- 

 of climates, are all consequences supposed to be derivable from the 

 assumption of the earth having once been thoroughly very ho 

 being now partially cooled by radiation of heat into the cold planetary 



