220 



THE WORLD'S ADVANCE 



Developing Plates by Motor Power 



When a large number of plates are to 

 be developed the following machine will 

 save considerable labor: 



The entire frame is made of J4" by 4" 

 white pine. 



The wheels, B, C and D should be 

 built according to the speed of the motor 

 since the wheel D must run very slow, 

 namely 30 r.p.m. The wheels, B and C, 

 are mounted on a shaft threaded at both 

 ends, with a burr on both sides. A 

 round-headed screw is passed through 

 the wheel, D, into the support, G. 



The rack, A, may be made as large as 

 desired to fit any number of trays. The 

 supports, / and K, are slotted at the top, 

 so that one rack can be easily taken out 

 and another put in its place. 



The stroke at E should be very short 

 and allowance made for adjustment at 

 F ; otherwise the rack will be tipped too 

 far and the developer will be spilled. 



The pitman, H, is made of y 2 " x %" 

 white pine, and slotted at connection 

 with F, so that it can be lifted off when 

 taking out the rack. 



The brace, P, connects the feet, M and 

 N. If the machine is to be used for large 

 plates or many trays, two pieces should 

 be put in, one at each end of N. 



With any small battery motor and two 

 or three dry cells this machine will oper- 

 ate successfully. 



Contributed by M. A. PIPER. 



Improved Non-acid Soldering Paste 



Zinc chloride, one of the constituents 

 of a non-acid soldering paste described 

 in the January issue of this magazine, 

 is not kept in stock by the average drug- 

 gist on account of the fact that this 

 chemical is very deliquescent, that is, it 

 absorbs moisture very rapidly. Ammo- 

 nium chloride, which does not possess 

 this undesirable quality, can be substi- 

 tuted with equal results in the formula. 



Ammonium chloride flux can be put 

 up very conveniently in old library paste 

 or tooth paste tubes which have previ- 

 ously been thoroughly cleaned. 



Contributed by 



REID L. KENYON. 



Marker for Spun Brass Caps 



Marking lines about spun brass caps 

 of various shapes can be done easily and 

 quickly with a tool of the following con- 

 struction : 



Referring to the accompanying draw- 

 ing, A is the work bench top, and B is a 

 long bolt with which fibre discs, F, in 

 graduated sizes are bolted to the bench. 

 The marker consists of a spacing bar, E, 

 bored with spaced holes to fit the point 

 of the marker, G, The space bar is 

 hinged to the bench top at C, while a 

 spring, D, serves to maintain a constant 

 pressure. The cap is marked by revolv- 

 ing it upon the fibre base, the marking 

 tool meanwhile scribing a line. 



Contributed by EARL B. WILLIAMS. 



