December 9, 1920] 



NATURE 



473 



themselves perforated in such a way that the posi- 

 tion assumed for each combination of the selector 



I 



Complcle rccciviog-p-inliog «pt4iratus, including receiving perloratur wiiii 

 relay anU pi inter. 



needles corresponding to a letter in Morse on the 

 strip causes coincidence of the perforations at one 

 point only, so that there is a clear 

 aperture through the whole pack 

 in a position corresponding to a 

 letter. The bottom plate is sup- 

 plied with compressed air at the 

 moment in the cycle of operations 

 corresponding to the printing of 

 a letter, and each aperture in the 

 fixed top plate communicates with 

 a small cylinder, in which moves 

 a piston actuating one of the type 

 bars, through levers like those of 

 an ordinary typewriter. Thus a 

 letter is printed corresponding to 

 the position of the coincidence of 

 the valve-plate apertures. 



The arrangement whereby a 

 variable feed is given to the strip, 

 according to the length of the 

 letter, is combined with that for 

 actuating the valve plates in ac- 

 cordance with the selection matle 

 by the needles. .\ reciprcKating 

 feed-rack is provided, which. 

 when required, can gear into a 

 spur-wheel on the same shaft as 

 the fecd-spr(H-ket. The length of 

 it.s downward travel while out of 

 pear depends upon the point where it U arrested 

 by the projection of one of a ^roup of spacing 

 NO. 2667, VOL. 106] 



levers. Normally, these levers are pushed out of 

 the way by the selecting needles, but where 

 neither of a pair of selecting needles ad- 

 vances — i.e. where there is a space signal 

 — a space lever continues to stand out, 

 thus limiting the movement of the rack to 

 the length of the letter. A sideways move- 

 ment is then given to the rack, putting it 

 into gear and causing the perforated strip 

 to feed forward, by exactly the length of 

 the letter just dealt with, during its return 

 journey. E!ach selecting needle, as it ad- 

 \ances, causes a hinged piece on the cor- 

 responding valve-plate extension to move 

 forward and to form a shoulder by the 

 side of the feed-rack, so that the sideways 

 movement of the feed-rack is also the 

 actual cause of the shifting of the selected 

 valve plates. It was mentioned above that 

 there are only ten valve plates, whereas 

 twenty selecting needles are provided. It 

 is only the lower group of ten needles that 

 1 ontrols valve plates, but the remainder 

 are required to actuate spacing levers. 

 .Although more selecting needles may pass 

 through the strip than those correspond- 

 ing to the letter in question, only the 

 proper number of slide valves are acted 

 upon by the rack, on account of the limita- 

 tion of its travel, by the spacing levers. 

 There are several other features, including 

 the method of withdrawal of the .selecting 

 needles and the timing of all the various 

 operations by means of cams, which we 

 cannot dwell upon. The whole apparatus, including 

 a small attached air-compressor, is driven by an 



Pm. tk— CrMd i)rp* prinMi iraa>Uilag from p«trorat«4 MortaMrip. 



electro-motor, so that no external source of com- 

 pressed air is required. 



