16 



♦ KNO>ArLEDGE ♦ 



[November 1, 1886. 



same time, or in refei-ence to measures taken to destroy by 

 exposure or otherwise the child itself whose predicted power 

 was feared. In one or other form the idea appears in every 

 solai' story, and in all solarised biographies— if I may be 

 allowed, for convenience, to coin such an expression. As 

 regards the bright light attending the birth of the solar 

 hero, or of the solarised teacher or legislator, we have a 

 number of curious illustrations. 



When Crisbna was born, his mother became resplen- 

 dent (remember hei'e how the rays of the rising sun at 

 the winter solstice shone full upon Virgo). The whole 

 cave was splendidly illuminated, says the Vishnu 

 Purana, " the quarters of the horizon were irradiated 

 with joy — the spirits and nymphs of heaven danced 

 and sang, the clouds emitted low, pleasing sounds." Beal, 

 in Ids " History of the ]!uddha," relates how, accord- 

 ing to Buddhist traditions, when the Saviour of the world 

 was born, " a divine light diffused itself around his person, 

 the Blessed One being heralded into the woiid by a super- 

 natural light." Zoroaster, the great teacher, of whom later 

 it was found that he sprang from an immaculate conception 

 by a ray of divine reason, was no sooner born than the 

 glory arising from his body enlightened the whole room, and 

 he laughed joyfully at his mother (Laughter and Light were 

 and are closely associated in the oriental mind). The legends 

 of the Hebrew patriarchs relate that at the birth of Moses 

 a bright light appeared and shone all around him ; his sub- 

 sequent adornment with " horns " or rays will be remem- 

 bered by all readers of the Greek and Latin versions of the 

 Old Testament. 



In early Christian art we find the same idea associated 

 with the birth of Christ. The gospel, however, in which 

 the event is recorded, is no longer regarded as canonical. 

 Indeed, nothing but an amazing intensification of Augustine's 

 power of believing, because a matter was beyond belief 

 (" Credo quia incredihile," he said), would enable men to ac- 

 cept the Protevangelion. Thus does the .story run in that 

 apocryphal gospel : — When INIary and Joseph were still three 

 miles from Bethlehem, and " in a desert place," Mary slid 

 to Joseph, " Take me down from off the ass, for that which 

 is within me mightily presses me." Then lie took her down 

 from off the ass, and found there a Give and put her into it. 

 He went towards Bethlehem for a midwife, and brought one 

 back with him. As they neared the cave a bright cloud 

 was seen over it. " But on a sudden the cloud became a 

 great light in the cave, so that their eyes could not be.ar it." 



It is noteworthy that Tertullian, Jerome, and other 

 of the Fathers state that Christ was born in a cave, and add 

 that " the heathen celebrated, in their day, the birth and 

 mysteries of their Lord and Saviour Adonis in this very 

 cave near Bethleliem ! " Canon Farrar appears to lean to the 

 idea that the old tradition was right, and that " the actual 

 place of Christ's birth was a cave," the same which " used to 

 be shown as the scene of the event even so early as the time 

 of Justin Martyr (a.d. 150)" — a dangerous doctrine, one 

 would suppose. 



Under the very aiipropriate title of '• The Handy ]\Iap of 

 the Moon," Messi's. Home, Thorn thwaite, k Wood have just 

 brought out a platinotvpe reproduction of a large chart of 

 our satellite, drawn by Mr. T. K. Mellor, F.E.A.S. The 

 image of the moon in this capital map is about ll'l inches 

 in diameter ; and the names of something like three hundred 

 of the principal formations are legibly and conspicuously 

 written against them upon it. It would be difficult to 

 devise anything more useful and convenient for reference, 

 by the light of a lantern, to the young working selonographer, 

 inasmuch as not the slightest crowding or confusion is per- 

 ceptible in any part of the map. 



THE NATURALIST'S LABORATORY. 



Contribution IV. 



N continuation of the subject of suitable illu- 

 ininatois for the laboratory, we have yet to 

 discuss the various forms of gas lamps and 

 burners of the most approved types. 



As to the gas itself, many important inven- 

 tions have been instituted in recent years to 

 economise in consumption and to increase 

 Illuminating power. Many of the bye-products of 

 distillation which are lost during the process of manu- 

 facture of the gas are of the first importance when 

 the intensity of its light is taken into considera- 

 tion, and lamps have been constructed to restore the 

 naj)hthalene in the case of the well-known al bo-carbon 

 burner, \vhilst the so-called similar " carboleine " is made 

 use of in Weston's patent " Omega " and the " Carburetter 

 Lamp." By these means considerable saving is etleeted ; as 

 much as twice the illuminating power is produced at about 

 one-third of the original expense. It is well for those who use 

 gas also to know of the existence of governors for regulating 

 the pressure of supply to the dome.stic pipes, as such varia- 

 tions cannot always be avoided in the gas mains. Un- 

 doubtedly the best form of apparatus in the market is that 

 called after its inventor, the "Stott" self-acting gas valve. 

 The object of this invention is to prevent over-pressure and 

 the consequent waste therefrom. The modus operandi is : — 

 Any excessive pressure immediately acts on an inverted 

 cup, sealed in an annular trough filled with quicksilver. 

 To the centre of the inverted cup is attached a spindle, at 

 the bottom end of which is a double-beat valve, a high 

 pressure raising the inverted cup, and thus closing the valve, 

 while a low pressure allows it to fall, thus opening it; for 

 instance, if 50 out of 100 lights lie turned off there will be 

 a corresponding increase of pr&ssure on the inverted cup, 

 raising and thereby closing the valve partially, so that for 

 every light turned off or on, or any increase or decrease at 

 the street mains, there is a corresponding opening or closing 

 of the valve in the governor, the pressure at the burner 

 thus being the same under any circumstances, and the 

 result being a saving of from 10 to 30 per cent., varying 

 according to the pressure at which the gas is supplied to the 

 consumers. 



The form of the gas.l)urner is said by Dr. A. Vernon 

 Harcourt to have added in the cases of the fishtail, bat- 

 wing, and Argand types, " as much as 20 or even 50 per 

 cent, to the light obtainable or commonly obtained from a 

 given consumption of gas. To produce a steady and 

 brilliant flame the gas must issue in a stow stream and 

 spread into a sheet, fan-shaped or cj'lindrical, of suitable 

 thickness, so that the hydrocarbons may be decomposed by 

 heat and partial combustion along the central plane, and 

 the resulting smoke may continue to burn and glow as it 

 spreads outwards for as long as is consistent 'with the 

 development of a sufficiently high temperature, and then 

 may meet the outer air so suddenly and over so large a 

 surface as to be completely consumed." 



Burners are also made by means of which heated air is 

 supplied to the flame, as already alluded to, in order to 

 increa.se its illuminating power. It has been found that 

 the ordinary gas-burner in general use does not ]jrovide 

 sufficient heat for the ignition and comi)lete combustion of 

 the carbonated gas, so that a waste of material results, and 

 with the loss of light the atmosphere becomes polluted by 

 the products of combustion added to by liberated free gas, 

 and thus the apartment is liable to be filled with a noxious 

 element and a powerful an.-esthetic • — conditions which 

 operate directly to make one drowsy and weak. To 



