The Montgomery advertiser., 1901-08-23
1he ADVERTISERS
 x HOME STUDY CIRCLE

soon leak and ruin the vacuum. The | these platinum wires by process of l nickle- plating. making small punches V and the stem thus fitted is inserted l in the bulb end and the joint fused
 at P. Copper wires are soldsred to the l outer ends of the platinum tips, to be | connected later to the plug D and ring
 R of the base" Platinum in form of
 wire costs as much as gold. and the smallest allowable quantity only is used. The bulb Is now filled with ordi- nary illuminating gas and enough cur. rent sent through the filament to heat | it to a degree learned by experience. | The thinnest portions will naturally heat the most, will decompose the gas
 In those vicinities and deposit the solid particles of carbon on the weak DOT tfons of the filament. What wa: previ-
 ously an irregular black brittle niament becomes harder, elastic and glossy al most like steel. Since the current is kept on for an instant only, the process
 is called "fias hing"
 The tubes of the lamps are fused to a common fixture that makes clusters of from three to ten, and by ground point it is attached to the vacuum pump. No single operation in the en- tire constr uction is so vital to the sue
 
 ing the air. An ordinary mecnanicai
 vacuum pump can easily produce
 vacu1m of twenty ne inches out or
 nossible thirty inches, as messur>o uy
 harometrtc column. This degree IS altogether insufficient for the incan-
 descent lamp. Commonly such me
 chemically operated piston pumps are , included in the equipment out theh
 direct portion of the Wo-k IS .h a | Ava mil exhaustion must be continued ioi
 eral hours longer by mercury pumps n
 tbe attempt to remove the remainihs
 thirtieth of the air. Ire Ieisslei
 tvne of this class is shown diagram
 n,tticallv in figure 45. It consists es.
 sent,aliy of two glass balos or ao4u' e, one quart capacity each. Fl cno nS, . connected at their lower ends oy si"eS tube; openings for the suct'on sue ol
 vi6ed at P and R; ground glass cheek , valves are at V and c; bulb or tuoe . containing phorrhoric anhydride TOT
 ahsorption of moisture is at D; three , lamps connected to wires are at |.
 Wien idle the mercury staAns at 'he , level shown in the cut. In pract"e
 large number of such pumps are at
 | ranged in rows. and such system o' n piping connects them that several nun f |
 U hausted. A three-way valve unner tnt 2 control of an attendant alternately I closes the pipe leading to R then con- Q meets R with the open air then conheci' |, | R with the suction P being always s suction end. The operation is then al r. follows: With R closed the mechanical
 pump exhausts directly from b2 ahe = the lamps thereby removing almost al n the air; then R is opened allowing at
 k@ GrtU d cury from B1 to B2; the rise of mercury a in B2 will close the valve c and oper a V. whatever air was in B2 would there e by be pushed out past all hope of re-en l. tering Exhaustion Is now made Iron d R drawing the mercury back to tn' l. original level as shown in cut; as tn' - mercury towers valve drops into It; l. socket and lastly valve c opens; what IT ever air remained in the lamp bulo e then expands so as to share its Voium' 1t With the emptied bulb B. The opera n tion takes place every two or three min - utes for several hours, so the air II B. the lamps becomes successively rari d fled until the vacuum is as perfect a
 may be desired. The final portion O '- the pumping is done while the fiament IS are heated, first to dull red, then t' [; ,br4lliant incandescence, thereby driv Il ing out any air or gases that may b e occulted in their pores. A small ga L. flame Is directed around the tube tha e supports each lamp, softening the glass II allowing the atmospheric pressure t' 'e close the walls, and then the tip | II fused; this both seals and disconnect 'ss the lamp. The brass shell and bas are then attached by means of plaste , ot Paris and the copper wires solderet = to the central plug and outer ring fo :, connecting witE contacts in the Ordl ii nary key socket. In the cut Thom 1 son. Houston type of this Is shown, bu 11 the adopllun of the Edison type with ', screw thread rolled on the outer shel d is becoming the general favorite. It ! , cheaper to make than many othe ,- forms, is easily removed from tn
 socket and does not rattle loose.
 ,l Combined photometric and electri d measurements are next made. Suf l. fcient current Is sent through tn If flament to bring its incandesccnce t l. the prede termined candle power, re "a qu;site voltage is noted with a volt d meter and label with this recor, V pasted to the lamp. In particular in 10 stance the standard sixteen canal ,s power may be secured when 109 volt 10 is impressed on the filament; the mex :, might take Ill or 112; all those approXi 3s mating 110 volts would ne put in on Ia class, those of l0i volts another, thoS ,- of 115 another and so on. So mucl l. experience has been attained and car !. exercised that the product is Surpris 10 ingly clos. to the calcula tions By pre- d determining the size and quality 0
 filaments lamps of different "efficien l. cies' can be secured: a great deal ha n been done of late years to improve tn ,- efficiency of operation; cheap or o ,o lamps are usually of low efficiency ,r that is, they will require -four, five O ~, more watts per candle power; four ,s rated as the lowest commercial limit "a three and a half common, three as tn ,r best If the variation of voltage ! , considerable In any given installation
 low economy lamps must be used 0 excessive breakage will result. Blu l. with hrst-class regulation the mos ,s economical lamps would be those talk -a .ng only three watts per candle power Ir Purely dependent upon regulation ', T, then, will result the ability to operat r- fifteen or only twelve lamps per cleo Ia trical horse power. Ordinarily centra "a stations have been unable t. main 3 tain a constan voltage throughou a their systems of wiring within 10 pe