Hi Northkey. Welcome.

Can you post an image showing where you understand your proposed solution to point to. Certainly, in taking the Phillips 66 to be the primary artefact that we were given and onto which we are asked to plot our radians and inches, six inches along the sixth radian actually falls just off the bottom of the map. It’s also important to understand that the printed scale on the map is grossly in error, and the Phillips is actually produced at marginally over 7 miles to the inch with a northing error of 5 degrees. Both these ‘errors’ are crucial and must be taken into consideration when converting from our given map coordinates to a modern Google Maps equivalent. I am finding that your proposal points broadly here:

What are you getting?

Thanks. The point I’m proposing is approximately the Neary/Sondgrath quarry area in Los Altos Hills, which I’ve marked on the Phillips 66 map.

I think there may be a misunderstanding regarding my reading of the two SIXes. I’m not proposing “six inches along the sixth radian.”

My reading is:

SIX = 6 o’clock from Mount Diablo, with 0 set to magnetic north.

SIX INCHES = six inches measured on the supplied Phillips 66 map.

Using the Phillips map’s printed scale of approximately 6.4 miles per inch, six inches represents about 38.4 miles. This is what led me to the PIT/quarry area.

I understand your point about the map actually measuring closer to 7 miles per inch and having a roughly 5° northing error when its positions are transferred to a modern map. However, I’m treating the Phillips 66 map as the primary solving artefact. Those discrepancies would not have been known to a solver simply following the map Zodiac supplied in 1970.

So my question is whether those corrections should be used to reinterpret the original six-inch instruction, or only when translating a position obtained on the Phillips map into modern coordinates.

The mark on the attached map is only intended to show the approximate Neary/Sondgrath quarry area, not an exact plotted coordinate. I’m currently travelling and doing this from my phone in a campervan, so please excuse the rather approximate map annotation.

Posted by: @northkey

↑

Thanks. The point I’m proposing is approximately the Neary/Sondgrath quarry area in Los Altos Hills, which I’ve marked on the Phillips 66 map.

I think there may be a misunderstanding regarding my reading of the two SIXes. I’m not proposing “six inches along the sixth radian.”

My reading is:

SIX = 6 o’clock from Mount Diablo, with 0 set to magnetic north.

SIX INCHES = six inches measured on the supplied Phillips 66 map.

Using the Phillips map’s printed scale of approximately 6.4 miles per inch, six inches represents about 38.4 miles. This is what led me to the PIT/quarry area.

Yes, it is easy to fall into misunderstandings over this, @Northkey. However, thankfully on this occasion my reading is intended to be precisely the same as the one you have detailed here. What we can work from in achieving our plot on the map, however, is the fact that, from an image available on the Zodiac Killer Facts website which shows an inch ruler laid out beneath a genuine copy of the map, a pixel by pixel analysis shows that whilst the scale of the map may be considerably out, the length of the line marked 0-8 is very, very accurately marking out 1.25 inches. We can then simply use this to measure out our distances from Mount Diablo. Specifically – and this is the crucial step – we can do this without needing to give any consideration to any conversion through miles whatsoever. It is trying to bring in an unwarranted conversion step where it is not required that gets us the wrong answers.

We have a length that equates to 1.25 inches on the map, and our candidate solution gives us the number of inches we are to mark out.

Proceeding in this direct way, you should find that 6 inches on the Phillips 66 takes you just off the bottom.

Posted by: @northkey

I understand your point about the map actually measuring closer to 7 miles per inch and having a roughly 5° northing error when its positions are transferred to a modern map. However, I’m treating the Phillips 66 map as the primary solving artefact. Those discrepancies would not have been known to a solver simply following the map Zodiac supplied in 1970.

Absolutely!! And this is precisely the line that we must take. The only reason I introduced the deduced errors is that they need to be factored in when converting a measured map coordinate into a modern mapping.

Posted by: @northkey

So my question is whether those corrections should be used to reinterpret the original six-inch instruction, or only when translating a position obtained on the Phillips map into modern coordinates.

The second, absolutely! Plotting it on the map just requires a compass and a graded inch ruler.

Posted by: @northkey

The mark on the attached map is only intended to show the approximate Neary/Sondgrath quarry area, not an exact plotted coordinate. I’m currently travelling and doing this from my phone in a campervan, so please excuse the rather approximate map annotation.

 file_000000001e908210a21ef226dee0c7411.jpg

Have fun on your camping trip, Northkey. 

Shaq

Actually, I was using an old somewhat rough and ready map overlay. Constructing the same much more precisely, I do find that your candidate just creeps onto the very bottom of the Phillips 66. It doesn’t, however, equate to the location you have marked above.

Posted by: @northkey

↑

However, I’m treating the Phillips 66 map as the primary solving artefact.

But are you, though?

I’m asking, because the location you have marked looks awfully close to what you would get if you used a modern accurate mapping, aligning your compass rose to actual true north (whereas true north on the Phillips is shown, but misaligned) and then proceeding out along this direction by 6 x 6.4 miles (even though the Phillips is actually scaled at 7.06 miles to the inch) and then plotting on the Phillips the point you reach via the modern mapping method, which would get you here:

 

Posted by: @northkey

Those discrepancies would not have been known to a solver simply following the map Zodiac supplied in 1970.

For context:

Hello, I’ve been following your work—which is very good, by the way—but I’m no expert.
A few years ago, I noticed what might be an error on the map; it struck me as odd, though I could be mistaken, but the map’s scale doesn’t match the actual distance.

Map scale: 1 inch = 6.4 miles

I noticed that from Lake Herman to Exit 680, the distance is 12.8 miles (approximately) on the PHILIPS map, while on Google Maps it’s only 2.5 miles.
??? !!!
Could this map have a manufacturing error (regarding the scale) or something similar?
Please correct me if I’m wrong.

Sorry if this has nothing to do with your excellent thread.

Best regards

Hi @Marclean.

Yeah, it looks like what you’re doing there is reading the scale marks the wrong way around. The 0, 1, 2, 4, 6, 8 are the miles already. You appear to be taking the 2 (miles) and then multiplying it by 6.4 to get an anomalous 12.8.

The map, which is only one section of the fold-out Phillips 66, is actually quite small. Something like a mere 7 inches across.

Oh yeah!!!!!!! I was taught the decimal system here in Brazil!!! I’m having trouble understanding it!!
Thanks for the reply—it cleared up a big question I had.

By the way, a few years ago I noticed that Zodiac used the scale at the bottom to draw the vertical line—it’s exactly the right size.

Anyway, I’ve been following your discussions and I like them.

The part I am still trying to understand is the discrepancy between your direct Phillips-map plot and the independent geographical check.

Geographically, the Neary/Sondgrath locality is approximately 197.24° true and 38.38 miles from Mount Diablo. With historical magnetic declination of about 17° E, that corresponds to approximately 180.24° magnetic — essentially magnetic south.

The distance gives a separate check. Using the Phillips map’s stated scale of approximately 6.4 miles per inch:

38.38 / 6.4 = 5.997 inches

So the independent geographical bearing and distance map back almost exactly to π from magnetic north / arm 6 / six inches on the Phillips map.

I understand from your mapping thread that your 12.4° / 7.02 mi-in corrections are intended only to translate a point already established on the Phillips map into modern coordinates, rather than to alter the original ruler-on-map construction.

That leaves me with a narrower question:

Why does your direct Phillips plot appear to place the six-inch arm-6 endpoint elsewhere when the independently measured geographic relationship between Mount Diablo and Neary is almost exactly 180° magnetic and 5.997 nominal Phillips-map inches?

I think that is the specific discrepancy worth isolating.

What your calculations show us here is that if the Phillips 66 were correctly aligned on true north and if the scale were 6.4 miles to the inch, then we could use a map north bearing of 197.0 and a measured length of 6 inches to pin-point Neary Quarry, as we should expect. But the Phillips 66 is not correctly aligned nor is it scaled at 6.4 miles to the inch. Hence, when we actually plot these coordinates on the map directly, they point to somewhere else.

And we want the coordinates of Neary on the map, because that is the mapping artefact we were given.

Operationally, if starting out from an actual on-the-ground bearing/range (degrees/miles) coordinate pair and wanting to determine where we would find the associated feature on the Phillips 66, were need to add 5° to our bearing and divide our distance by 7.06 miles to the inch. Thus, for Neary, we would get:

Bearing: 197 + 5 = 202°

Range: 38.38 / 7.06 = 5.436 inches.

Try it, plot these coordinates on the Phillips. 👍

Posted by: @shaqmeister

↑

Operationally, if starting out from an actual on-the-ground bearing/range (degrees/miles) coordinate pair and wanting to determine where we would find the associated feature on the Phillips 66, were need to add 5° to our bearing and divide our distance by 7.06 miles to the inch. Thus, for Neary, we would get:

Bearing: 197 + 5 = 202°

Range: 38.38 / 7.06 = 5.436 inches.

Try it, plot these coordinates on the Phillips. 👍

Here, of course, I’m specifying the bearing from map north, marked by the little direction arrow over the encircled ‘66’ on the left of the map. Does that now make sense?

I think I can now clear up the point we were discussing about Neary and the Phillips 66 map, and there is also a new development in the cipher hypothesis which may be more interesting than the geographical argument.

First, a correction to my earlier posts.

Shaq, I now understand the distinction you were making. I was conflating two different things: the relationship in real-world geography and the physical geometry of the Phillips 66 map itself.

In real-world geography, the relationship is remarkably clean. Using the published locality coordinates for Mount Diablo and Neary/Sondgrath, Neary is approximately 38.38 miles away on a true bearing of about 197.2°. With the historical magnetic declination near Mount Diablo at roughly 17° E, that is essentially 180° magnetic — position 6 on Zodiac’s 0–3–6–9 dial.

And:

38.38 / 6.4 = 5.997 inches.

So in real geography the relationship really is, to a very close approximation:

π radians from magnetic north / position 6

+

six nominal Phillips-scale inches.

That calculation is real, and I think it remains interesting.

But that is NOT the same as saying that a ruler placed directly on the Phillips 66 map lands on Neary.

Shaq’s point is correct here. The Phillips map itself has its own physical geometry. His reconstruction places the real-world Neary location on that map at approximately 202° from map north and about 5.436 physical inches from Mount Diablo, rather than at the direct six-inch position-6 endpoint.

So I withdraw my earlier implication that the Phillips 66 map itself directly demonstrates a six-inch hit on Neary. It does not, at least not from the map material/reconstruction we currently have.

I think this actually leaves the hypothesis in a cleaner position, because we should not need Neary to manufacture the plaintext in the first place.

There is now another possible piece of the mechanism.

On page 5 of the Little List letter Zodiac wrote:

“Radians + # inches along the radians.”

Immediately at the # he drew an upward arrow.

The obvious conventional relationship worth testing is:

↑ + 3 = #

i.e. SHIFT + 3 produces # on the standard US keyboard/typewriter arrangement.

I am NOT claiming that this proves Zodiac intended a keyboard instruction. But it gives us a very specific operation to test rather than an arbitrary one:

SHIFT 3.

So I applied the simplest literal positional interpretation to Z32: cyclically shift all 32 cipher positions forward by three, with wraparound:

1→4

2→5

3→6

…

29→32

30→1

31→2

32→3.

My existing candidate is:

ATSIXSIXINCHESFROMMOUNTDIABLOPIT

After exactly that three-position cyclic shift it becomes:

PITATSIXSIXINCHESFROMMOUNTDIABLO

or, with the word boundaries restored:

PIT AT SIX SIX INCHES FROM MOUNT DIABLO

Nothing else has been rearranged. The complete final three-letter word moves to the front and the remaining phrase retains its word order.

I have tried to falsify this interpretation rather than stopping at the attractive result.

I tested other reasonably obvious uses of “3”: every-third-symbol readings, period-3 arrangements, applying ±3 to values obtained from the Z408/Harden key, the Concerned Citizen variants, direct Z340 substitution values where symbols can safely be identified, three radians, and three inches.

None produced comparable structure.

That does not prove SHIFT 3 is the intended meaning of ↑#, but at present I see no justification for applying the 3 anywhere else. So I am restricting the hypothesis to the single operation above rather than allowing “3” to become an adjustable parameter.

There is then a second, and I think rather interesting, consequence concerning PIT.

Previously I was very explicit that the Z32 repeat constraints gave me only:

AT SIX SIX INCHES FROM MOUNT DIABLO ??T

The T is constrained because Z32 positions 2 and 32 contain the same cipher symbol. Since position 2 in this candidate is T, position 32 must also be T.

P and I were not cipher-forced.

That was one of the weakest parts of my original proposal, because I was completing ??T as PIT from the geographical quarry/pit evidence.

But the Little List hint itself gives us something I had not previously considered:

RADIANS → π

and π written alphabetically is:

PI.

So we now have two independently motivated components:

π → PI

and the repeated-symbol constraint:

position 32 → T.

Together:

PI + T = PIT.

Again, I want to be careful about what I am claiming. π → PI is a rebus/textual interpretation, not a conventional substitution-key derivation. But it is significant that the two previously unconstrained letters in PIT can be obtained from the explicit RADIANS hint, while the final T is independently fixed by the cipher repetition.

With the possible SHIFT 3 instruction, that gives the complete reordered statement:

PIT AT SIX SIX INCHES FROM MOUNT DIABLO.

There is another structural point worth mentioning.

Once we take the shifted form:

??? AT [direction] [distance] INCHES FROM MOUNT DIABLO

the complete text must still contain exactly 32 letters.

The fixed parts consume 26 letters, leaving six letters in total for [direction] + [distance].

The repeated-symbol identity corresponding to original positions 6=14 forces the first letter of the distance to equal the final S of INCHES. So the distance begins with S.

Within the restricted 0–3–6–9 dial vocabulary and ordinary written number distances, SIX is the three-letter solution. That leaves three letters for the direction, and among ZERO / THREE / SIX / NINE, only SIX has three letters.

Thus within this deliberately restricted map grammar we recover:

??? AT SIX SIX INCHES FROM MOUNT DIABLO

without choosing SIX/SIX from the Neary geography.

The other repeated-symbol identity then fixes the final letter of the three-letter destination as T:

??T AT SIX SIX INCHES FROM MOUNT DIABLO.

And the radians hint provides the possible PI:

π + T → PIT.

That changes how I now regard the Neary result.

I no longer think Neary should be presented as the thing that supplies P and I or as proof that the direct Phillips construction lands on the quarry. That was too strong.

Instead there are now two separate questions:

1. Does the internal Z32/Little List construction really encode

PIT AT SIX SIX INCHES FROM MOUNT DIABLO?

2. Independently, why does the real-world Mount Diablo → Neary/Sondgrath relationship happen to be almost exactly six nominal Phillips-scale inches at position 6 after magnetic north is taken into account?

The second remains a striking geographical correspondence, but it should not be allowed to determine the first.

And Section 6 remains where I placed it originally: a secondary, post-hoc observation only. It was found after the quarry connection and should not be used as an input to derive the solution.

So my revised position is narrower than before in one respect and stronger in another:

I retract the claim that the physical Phillips 66 map itself directly places the six-inch position-6 endpoint on Neary.

But the plaintext hypothesis no longer needs that claim.

The internal proposal I am now testing is:

↑# → SHIFT 3

Radians → π → PI

Z32 repeats + restricted map grammar → ??T AT SIX SIX INCHES FROM MOUNT DIABLO

PI + T → PIT

giving:

PIT AT SIX SIX INCHES FROM MOUNT DIABLO

Still a hypothesis, not a claimed solution.

But importantly, Neary is now a test of the hypothesis rather than an input used to construct the plaintext.

Still camping.