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x = 29, y = 47, rule = B3/S23 19b2o$19bo$17b3o16$17b2o$17b2o2$8b2obo$8bob2o$26b2o$26bo$24bobo$24b2o 2$9bo$9b3o$o11bo$3o8b2o14bo$3bo22bobo$2b2o23bo7$bo$bobo$b3o$3bo11b2o$ 15bo$16b3o$18bo! ---- #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ ZOOM 8 X 0 Y 0 GPS 20 LOOP 157 PAUSE 2 T 156 PAUSE 2 WIDTH 480 HEIGHT 480 THUMBSIZE 2 ]]
Pattern type Conduit
Conduit type Composite
Input Herschel
Number of cells 56
Output orientation Turned left
Output offset (17, -41)
Step 156 ticks
Recovery time
(ignoring FNG if any)
62 ticks
Minimum overclock period
(ignoring FNG if any)
Spartan? Yes
Dependent? No
Discovered by David Buckingham
Year of discovery 1996

L156 is a composite conduit, one of the original sixteen Herschel conduits, discovered by Dave Buckingham on August 7, 1996.[1] It is made up of three elementary conduits: HLx69R, RF28B, and BFx59H. After 156 ticks, it produces a Herschel turned 90 degrees counterclockwise at (17, -41) relative to the input. Its recovery time is 62 ticks. It can be made Spartan by replacing the snake with an eater 1 in one of two orientations. In the pattern shown in the infobox, a ghost Herschel marks the output location.

Three variants are shown below. The first is the one in the infobox. The second uses an alternative RF28B to produce a glider in a different direction. The third uses an RNE-19T84 to produce two extra gliders and convert the conduit into a period doubler.

x = 59, y = 171, rule = B3/S23 44b2o$44bo$42b3o16$42b2o$42b2o2$33b2obo$33bob2o$51b2o$51bo$49bobo$49b 2o2$34bo$34b3o$25bo11bo$25b3o8b2o14bo$28bo22bobo$27b2o23bo7$26bo$26bob o$26b3o$28bo11b2o$40bo$41b3o$43bo16$44b2o$44bo$42b3o16$42b2o$42b2o2$ 33b2obo$33bob2o6$34bo$34b3o$25bo11bo$25b3o8b2o14bo$28bo22bobo$27b2o23b o4$49b2o$49bobo$51bo$26bo24b2o$26bobo18b2o$26b3o18bo$28bo11b2o6b3o$40b o9bo$41b3o$43bo16$44b2o$44bo$42b3o16$42b2o$42b2o2$33b2obo$33bob2o2$18b 2o$18bo16bo$16bobo15bobo$16b2o16bobo$32b3ob2o20bo$31bo24b3o$25bo6b3ob 2o17bo$25b3o6bob2o17b2o$28bo$3bo23b2o$b3o48b2o$bobo47bo2bo$bo50b2o4$ 26bo$26bobo$15b2o9b3o$2b2o11b2o11bo11b2o$3bo36bo$3o38b3o$o42bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART THUMBSIZE 2 ZOOM 10 WIDTH 480 HEIGHT 1750 X 8 GPS 16 PAUSE 2 T 73 PAUSE 2 T 77 PAUSE 2 T 97 PAUSE 2 T 108 PAUSE 2 T 156 PAUSE 2 T 399 PAUSE 2 LOOP 157 ]]
(click above to open LifeViewer)
RLE: here Plaintext: here

The third L156 variant produces an extra block, which is period-doubling. In the viewer, a Herschel coming 77 generations earlier will be blocked. For it not to be period-doubling, it must be:

  1. deleted using a reflector (such as the p8 bumper + dependent conduit);
  2. deleted using a set of conduits (e.g. R64 + F117).

L156 as an injector

The BFx59H in the second variant of the L156 can act as an injector.

Warning: The following viewer will pause 10 times.

The viewer below shows the injection of a Herschel into an existing track using a L156. Ghost Herschels mark the output locations, and a duoplet marks the block produced in the period-doubling L156 in the northeast.

x = 133, y = 144, rule = B3/S23 100b2o$101bo$88bo11bo$88b3o9b2o$91bo$78b2o10b2o39bo$79bo50bobo$79bobo 48bobo$65b2o13b2o49bo$65b2o36b2o15bo$103b2o15bo$120b3o$59b2o61bo$59b2o $63b2o$63b2o15bo$80bo$80b3o$82bo11b2o$58b2o34bo$58b2o35b3o$97bo$78bo3b 2o$77bobo3bo$77b2o3bo$81bo$77b5obo$72b2o3bo4bobo$62bo9bo6bo2bobo$63bo 6b3o5b2o3bo$60b3o$60bo14$70b2o$70b2o$o$b2o58b2obo$2o59bob2o3$63bo$62bo bo$62bobo$60b3ob2o20bo$59bo24b3o$53bo6b3ob2o17bo$53b3o6bob2o4b2o11b2o$ 56bo13b2o$39b2o14b2o$39b2o39b2o$79bo2bo$80b2o$33b2o$33b2o$37b2o$37b2o 15bo$54bo$54b3o$56bo11b2o$32b2o34bo$32b2o35b3o$61bo3b2o4bo$52bo3b2o2bo bo3bo$51bobo3bo2b2o3bo$51b2o3bo7bo$55bo4b5obo$51b5obo2bo4bobo$46b2o3bo 4bobobob2obobo$46bo6bo2bobob2obob2o$44b3o5b2o3bo16$44b2o$44b2o2$35b2ob o$35bob2o$20bo$18b3o$17bo$17b2o2$36bo$36b3o$27bo11bo$27b3o8b2o14bo$30b o22bobo$29b2o23bo4$51b2o$51bobo$53bo$28bo24b2o$28bobo18b2o$17b2o9b3o 18bo$17b2o11bo11b2o6b3o$42bo9bo$43b3o$45bo16$91b2o$91bobo$91bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART THUMBSIZE 2 ZOOM 6 WIDTH 700 HEIGHT 900 GPS 20 X 3 PAUSE 2 T 73 PAUSE 2 T 97 PAUSE 2 T 156 PAUSE 2 T 220 PAUSE 2 T 231 PAUSE 2 T 293 PAUSE 2 T 295 PAUSE 2 T 317 PAUSE 2 T 328 PAUSE 2 T 376 PAUSE 2 T 826 PAUSE 2 LOOP 827 ]]
(click above to open LifeViewer)
RLE: here Plaintext: here
  • Pause 1: the Herschel reached generation 4 of the R-pentomino.
  • Pause 2: the Herschel reached the BFx59H, the exact conduit that the gliders will be injecting into.
  • Pause 3: the original Herschel reached the R64 conduit. The gliders are in the position to be injected.
  • Pause 4: the original Herschel passes the R64. The new Herschel is in the process of injecting.
  • Pause 5: the new Herschel is successfully injected.

Pauses 6-10 show the procedure of removing the new Herschel that is up to 495 ticks separated. This does not work if the one Herschel is 503 or more ticks separated, and the conduit will break if the Herschels are separated by 496-502 generations.

  • Pause 6: the original Herschel reached generation 4 of the R-pentomino.
  • Pause 7: the new Herschel passes the R64. By using an RNE-19T84 instead of the standard L156 catalyst, the new Herschel can be blocked.
  • Pause 8: the original Herschel reached the BFx59H. It is in the position to block the new Herschel.
  • Pause 9: the original Herschel (which is currently in a temporary R-pentomino phase in the BFx59H) leaves a block (in where the duoplet originally was), which will remove the new Herschel.
  • Pause 10: the new Herschel was destroyed by the block. The original Herschel evolves normally, continuing along the Herschel track.

Note that you can instead remove the original Herschel by putting a block in the position of the duoplet. The 2 conduits above (R64 and F117) and the welded eater 5 makes sure that the block is always absent when a new Herschel 503+ generations later comes. This conduit does not work for Herschel spaced 496-502 generations apart.


  1. David Buckingham (October 12, 1996). "My Experience with B-heptominos in Oscillators". Paul Callahan's Page of Conway's Life Miscellany. Retrieved on November 9, 2020.

External links