Build A Pennsic Sundial

Fred Blonder's Sundial for Clan Cambion

For Pennsic XXVI, Fred Blonder built a vertical sundial. While the design was complicated by his decision to make it correct only for mid-August at Pennsic, thus incorporating seasonal corrections and daylight-savings-time into the calculations, use of the sundial was greatly simplified by this. Incorporating those calculations into the design rendered the resulting instrument less general (it's only accurate in August), a user who wishes to read the time need not deal with the seasonal corrections needed for a year-round sundial and the lattitude/longitude corrections of a portable one. Below are the angles he computed, so that others can build similar sundials if so inclined. I, for one, would love to see sundials sprinkled around the site. Perhaps a couple of large-ish ones for the merchant areas?

As he was camping with Clan Cambion, Fred painted his sundial to resemble the clan's device -- sable, with a checkered border and a bar sinister, argent. The colour made it a bit difficult to read from a distance, unfortunately, but it did keep accurate time. It was positioned at the gate of the Clan Cambion campsite. Being a South-facing sundial, it had to be on the inside of the gate. (Clan Cambion was camped on the South side of Howard's Fenway.)

Table Of Angles -- build your own!

The text from here down is by Fred Blonder:

Angles are measured increasing counterclockwise, with zero being straight down. Facing the dial from the south you see:

  <-- West  East -->
-90 ======================================================================++------ +90
         /||\
        / || \
       /  ||  \
      /   ||   \
     /    ||    \
    /     ||     \
  -45           +45
          00

The vertical "zero" line is duplicated and separated by the thickness of the gnomon.

The gnomon:

    This	|\ <- 49.03 Degrees
    side	| \
    attaches ->	|  \
    to		|   \
    dial	|    \
    face.	|     \ <- 40.97 Degrees
		======================================================================

The number of decimal places is absurd. I can't measure that accurately. ;-)

   Time    Shadow angle
A.M.:

   7:30 - -88.376789
   7:35 - -86.722532
   7:40 - -85.070620
   7:45 - -83.422216
   7:50 - -81.778465
   7:55 - -80.140482

 8:00 - -78.509349
   8:05 - -76.886106
   8:10 - -75.271748
   8:15 - -73.667219
   8:20 - -72.073410
   8:25 - -70.491153
   8:30 - -68.921219
   8:35 - -67.364317
   8:40 - -65.821093
   8:45 - -64.292127
   8:50 - -62.777933
   8:55 - -61.278962

 9:00 - -59.795601
   9:05 - -58.328176
   9:10 - -56.876950
   9:15 - -55.442128
   9:20 - -54.023862
   9:25 - -52.622247
   9:30 - -51.237328
   9:35 - -49.869105
   9:40 - -48.517530
   9:45 - -47.182515
   9:50 - -45.863933
   9:55 - -44.561622

10:00 - -43.275386
  10:05 - -42.005000
  10:10 - -40.750212
  10:15 - -39.510747
  10:20 - -38.286304
  10:25 - -37.076568
  10:30 - -35.881202
  10:35 - -34.699856
  10:40 - -33.532169
  10:45 - -32.377764
  10:50 - -31.236258
  10:55 - -30.107258

11:00 - -28.990366
  11:05 - -27.885176
  11:10 - -26.791280
  11:15 - -25.708265
  11:20 - -24.635716
  11:25 - -23.573217
  11:30 - -22.520352
  11:35 - -21.476701
  11:40 - -20.441847
  11:45 - -19.415375
  11:50 - -18.396867
  11:55 - -17.385910

P.M.:

12:00 - -16.382090
   0:05 - -15.384997
   0:10 - -14.394221
   0:15 - -13.409355
   0:20 - -12.429994
   0:25 - -11.455734
   0:30 - -10.486176
   0:35 -  -9.520919
   0:40 -  -8.559566
   0:45 -  -7.601723
   0:50 -  -6.646996
   0:55 -  -5.694992

 1:00 -  -4.745321
   1:05 -  -3.797594
   1:10 -  -2.851421
   1:15 -  -1.906416
   1:20 -  -0.962191
   1:25 -  -0.018360
   1:30 -   0.925463
   1:35 -   1.869665
   1:40 -   2.814633
   1:45 -   3.760753
   1:50 -   4.708413
   1:55 -   5.658001

 2:00 -   6.609906
   2:05 -   7.564521
   2:10 -   8.522235
   2:15 -   9.483443
   2:20 -  10.448541
   2:25 -  11.417925
   2:30 -  12.391994
   2:35 -  13.371149
   2:40 -  14.355793
   2:45 -  15.346332
   2:50 -  16.343172
   2:55 -  17.346722

 3:00 -  18.357394
   3:05 -  19.375600
   3:10 -  20.401755
   3:15 -  21.436274
   3:20 -  22.479575
   3:25 -  23.532074
   3:30 -  24.594190
   3:35 -  25.666340
   3:40 -  26.748940
   3:45 -  27.842405
   3:50 -  28.947148
   3:55 -  30.063578

 4:00 -  31.192099
   4:05 -  32.333111
   4:10 -  33.487007
   4:15 -  34.654170
   4:20 -  35.834977
   4:25 -  37.029791
   4:30 -  38.238962
   4:35 -  39.462826
   4:40 -  40.701702
   4:45 -  41.955888
   4:50 -  43.225662
   4:55 -  44.511277

 5:00 -  45.812959
   5:05 -  47.130904
   5:10 -  48.465277
   5:15 -  49.816206
   5:20 -  51.183781
   5:25 -  52.568049
   5:30 -  53.969015
   5:35 -  55.386635
   5:40 -  56.820815
   5:45 -  58.271406
   5:50 -  59.738206
   5:55 -  61.220952

 6:00 -  62.719322
   6:05 -  64.232932
   6:10 -  65.761333
   6:15 -  67.304013
   6:20 -  68.860394
   6:25 -  70.429833
   6:30 -  72.011625
   6:35 -  73.605000
   6:40 -  75.209128
   6:45 -  76.823121
   6:50 -  78.446037
   6:55 -  80.076882

 7:00 -  81.714618
   7:05 -  83.358166
   7:10 -  85.006410
   7:15 -  86.658207
   7:20 -  88.312394
   7:25 -  89.967791

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A portable ring-style sundail for Pennsic

(* email D. Glenn Arthur Jr. * Glenn's Pennsic page * Fred's pre-calibrated vertical sundial * Fred's pre-calibrated ring sundial * Glenn's camping without a cooler page * Pennsic photo preview page * Map Of My Web Pages * my main page * about me * musings and observations * me the musician * writings * events * humour *)