THE NOMOGRAM
Some nomograms for sundials use a logarithmic portrayal because the
nomogram is often an additive device, and multiplication is done by adding
logarithms. However, some nomograms use division directly (N or Z) and some
use multiplication directly (circular), so, there is variety. Here are several types:-

type 1      | | |        additive nomogram     C = L + R   must use logs for * and /
type 2      | \ |        dividing nomogram     C = L / R    no logs for division
type 3      ( | )       multiplying nomogram C = L * R   no logs for multiplying
type 4      \ /_       adds reciprocals         1/C = 1/L + 1/R

For those who wish to design nomograms and understand them in more detail,
and sundial plates using nomograms,
here are some highly detailed notes (if
you buy the big book
either printed or online download) on doing it, they
will save you a lot of time.
The process for the horizontal dial is shown, the
vertical dial being the same but co-latitude, which is also s
hown. Further, the
DeltaCAD macro:  
nomogram.bas   builds vertical and horizontal dials, but since
DeltaCAD (as I have it) only does
natural logs as opposed to base 10, these
macros use Napierian logs.
All nomogram files in one ZIP file,
DeltaCAD macro, and the
Lazarus/Pascal source and
executable, test skeleton
programs, and more.
type 3
type 2
type 1
DeltaCAD macro is a complete v and h dial, a sunrise/set, a polar/meridian
dial with calendar data nomogram (both the three vertical line as well as the N
or Z nomogram), and a vertical decliners SD, SH, and DL with the v-dec hour
lines worked using SH and DL. The DL macro choice has two variations, the
second showing the use of differing line separations (xL, xC, xR) and the
modulus (scale) of the right line (mR) which you may change. Also has the
analemmatic dial nomogram. Does nomograms type 1,2, and 3.

Lazarus/Pascal code for the h, v, m/p, v-dec dials, and sunrise/set times all in
one ZIP file. Does nomograms type 1, 2, and 3. In essence, everything the
DeltaCAD macro does
except exporting the images, which needs a screen
screen capture program such as this (I have NOT used it, I use PhotoMax Pro).

Printed nomograms from both DeltaCAD and Lazarus/Pascal are in PDF form.
The nomograms are also in the free
appendices. This book of printed
nomograms may be lower quality print than if you run the DeltaCAD or the
Lazarus based program, which you are encouraged to do. the appendices
however have very high quality nomograms.

NOTE: Chapter 32 in Illustrating Time's Shadow covers more detail,
however, the most detail is in
Supplemental Shadows and takes some
30 pages, and supplements chapter 32, and go
es into more detail on
line separation, modulus (line scaling), and details on where "0" is

on the three common nomogram types. The free appendices to
Illustrating Time's Shadow have the nomograms in appropriate
sections, and the formula appendix also  has a short summary of the
three nomogram types, their formulae supported, and where '0' is, and
other issues with 0.

Documents online for nomogram design are:-

The Art of The Nomogram - read this first
Graphical and Mechanical Computation   
Creating nomograms with pynomo software  
JAVA online nomogram builder
A nomogram that is not type 1, 2, nor 3.
This is a quadrant of an equatorial dial.
Not really a nomogram, more a
teaching aid for correctly
drawing
some h-dial (and v-dial) hour lines
from an equatorial dial.