Shaq, I owe you an apology.

I mistakenly believed that the image with the grid pattern was yours and that it was an older version of the image you posted here in September.

I should have checked this more carefully before making that claim, and I sincerely apologize for the mistake.

I’ll get back to the other points when I have more time.

One final psychological prompt, a reductio ad absurdum perspective.

We are given 1.) a map and 2.) a distance in inches. The latter is in precisely the form we need to measure out those very inches (2.) on this very map (1.). That should be it.

Let us do as you propose, however.

We take the number of inches (2.) that we were given and apply the (erroneous) printed scale found on the map to derive an erroneous distance in miles. We then find ourselves a different map (1a.) and we deduce the number of inches (2a.) on this map that corresponds to our deduced distance in miles. We take this doubly-deduced inch distance (2a.) and we apply it to our arbitrarily chosen map (1a.) to discover where it gets us.

It gets us to a different place, because the printed scale on the Phillips map is wrong.

But then you will see—and this is the absurdity—that all you have done is applied a series of unnecessary, erroneous and uncalled-for conversions to get back precisely to the very point you started from: measuring a distance in inches (2a.) on a map (1a.).

Having been averse, for whatever reason, to simply measuring out the given inches on the given map, you find nonetheless that the end point of your wandering is merely to measure out some or other different inches on some different map.

We can discount all of this extra circular nonsense as not being something we could be expected to pursue.

We were given a distance in inches (2.) and we were given a map (1.).

Posted by: @shaqmeister

↑

We can discount all of this extra circular nonsense as not being something we could be expected to pursue.

More to the point, had The Zodiac wanted us to use some other map he would have given us that other map and a distance in inches for it. Had he merely wanted us to not use the Phillips he would have given us the distance in miles. Both these alternatives would be as free from ambiguity and capable of producing the intended result without confusion as is the method he did use.

Posted by: @northkey

↑

Shaq, I owe you an apology.

I mistakenly believed that the image with the grid pattern was yours and that it was an older version of the image you posted here in September.

I should have checked this more carefully before making that claim, and I sincerely apologize for the mistake.

I’ll get back to the other points when I have more time.

No need to apologise, @Northkey. It very possibly could have been something that I posted. Without a link, though, I would have difficulty trying to find it.

For myself, I can recognise that I have come to the limit of any assistance I am able to contribute at this time beyond just repeating points I have already made but in different words. My purpose is to present logical analyses and challenge errors, not merely to change minds. I feel I have gone as far as I can with that here.

Posted by: @shaqmeister

↑

We can discount all of this extra circular nonsense as not being something we could be expected to pursue.

We can go further.

1. Were The Zodiac to be of the belief that the Phillips 66 is accurately scaled and oriented, then he would not have entertained the additional steps you introduce because he would be aware that it would produce precisely the same result on any other accurate map as on the Phillips 66. The extra work is redundant under this assumption and he would just use the Phillips and a ruler.
2. Were The Zodiac to be of the belief, or even under suspicion, that the Phillips 66 is only loosely scaled and oriented, then he would have known that adding in the extra steps to get back to inches via some intermediary map will merely introduce an error. He could not pursue this nonsensical route, even had he wanted to, without explicitly telling us that’s what the method should be. He would be forced, then, to go back to using the Phillips and a ruler.
3. There is no 3.

I have just one more question, one that steps back from all the detail and considers the problem from the very beginning, just as if we had seen it for the first time. In asking this one important question, though, I am merely wanting to get a sense of how early in your reasoning with this problem have you gone astray. To me, it appears that you have erred right at the very beginning, and I’m just wanting to check if that is so. The question I would ask, then, is this:

Why is it—given that we can only plot a distance on any map using, say, an inch ruler, and given that we are provided with a distance in inches—why is it that you are drawn to give even a moment’s attention to some line on the map that tells you what its approximate conversion scale is? What are we given that requires converting?

The Phillips 66 map can provide the instructions, the bearing reference and the distance scale without necessarily requiring its physical geometry to determine the final geographical location.

This does not depend on whether Zodiac knew the map was inaccurate.

If he believed the map was accurate, using its printed scale to establish a geographical distance would be entirely consistent with that belief.

If he suspected the map was inaccurate, the distinction between its printed scale and its physical geometry would become even more relevant, not less.

And your own Google Maps image illustrates the practical problem.

When you show us on Google Maps where your P66 plotting leads, you have somehow transferred that location from one map to another — in other words, converted inches into miles. Now the result is displayed on a map where the distance can be measured in miles, and that distance remains the same regardless of whether you zoom in or out. The physical scale on the screen changes, but the geographical distance remains the same.

That is why the map’s conversion scale matters. It provides a geographical distance that can be checked independently of the physical dimensions and distortions of the original map.

Google Maps may show us what the area looks like today, but that is not what interests me. I want to examine what was actually there in the 1970s, using maps from that period.

So tell me, why can’t I use the printed scale on the P66 map to establish a geographical distance and examine where my interpretation of the code and map leads me on more detailed maps from the 1970s, while you can show us where your interpretation leads on Google Maps?

You may prefer the ruler-only interpretation, but neither of your two scenarios establishes that it is the only valid way to use the map.

The third option has already been explained several times.

Posted by: @northkey

↑

When you show us on Google Maps where your P66 plotting leads, you have somehow transferred that location from one map to another — in other words, converted inches into miles.

I have done no such thing. I have identified where the coordinates point to on the Phillips 66, looked for that place on Google Maps, and put a pin in it.

I would ask the crucial question again: what have we been given that requires conversion, for any reason?

Posted by: @shaqmeister

↑

I would ask the crucial question again: what have we been given that requires conversion, for any reason?

And just to clarify, by “for any reason” I mean for any purpose that is needed to get us to the location, not just because we can.

And just to help cleanse your thinking of further error, in 2026 I am viewing Google Maps on a computer screen. It is not plotted for me in either inches nor miles. It is rendered in screen pixels. Accordingly, since I have not needed to consider its distance from anywhere whatsoever to enable me to locate the same place on this map as located on the Phillips, neither have I had to first perform any conversion from inches to pixels.

Im not sure why you would think that Google Maps, as a screen map, is “in miles.”

Posted by: @northkey

↑

You may prefer the ruler-only interpretation, but neither of your two scenarios establishes that it is the only valid way to use the map.

The correct answer to the question “what have we been given that must be converted before it can be plotted,” when you provide it, will establish precisely this. Because, if we can achieve a direct plotting of the given inches on the given map then, unless we are explicitly told to start throwing in unnecessary conversions just to get back to plotting out a different inch distance on a different map, we should not be doing any such thing.

There is nothing we can’t use directly and we are not told to do anything different. We will apply the direct method.

This is how you can know your proposal is not a reasonable nor valid one.

Posted by: @northkey

↑

I want to examine what was actually there in the 1970s, using maps from that period.

Perfect. Just note the place that The Zodiac identifies on the Phillips and find it on your 1970s map. This is the correct method of transferring a specific location from one map to another. Any other indirect method risks you arriving at a different place, as you have been shown. As is demonstrably the case here.

Had you considered how the situation sits in relation to the bearing we were given? Although not a conversion, as such (rather a shift), because it was his choice to measure his bearing from magnetic north, rather than true north, he had to explicitly tell us so. Otherwise, we would have simply used true north and got it wrong. Of course, acknowledging this potential, he did tell us. He said nothing about any conversion from his given and perfectly serviceable inch length. 🤔

Posted by: @northkey

↑

That is why the map’s conversion scale matters. It provides a geographical distance that can be checked independently of the physical dimensions and distortions of the original map.

This, if you spend enough time thinking about exactly just what you have said, is an absolutely nonsensical statement. I had wanted to say an insane statement.

You are claiming that an erroneous scale written on a map somehow, by just accepting it for what it says, provides an “independent check” of the geographical distance between two places. You have to rethink everything about what you just written here.

A “check” is an extra processes we perform to demonstrate that the result we had just produced is actually a correct result. We determine success of our “check” by the fact that our deduced result and the result from the check are the same.

Now, whether you like it or not, the “geographical distance” between the summit of Mount Diablo and a place just south east of Stevens Creek Reservoir is about 42 miles. We cannot change this fact by any process of either accurate or inaccurate mapping. If, then, we indiscriminately apply the printed scale on the Phillips 66 to the measured length between these two places of 6 inches, which produces a “geographical distance” of only 38 miles, then our check has failed. This is how “checks” work and how they are used to tell us when something in our calculation is wrong.

You are so fixated on scales and coordinates and conversions of distances.

The only consistency that we must always have when transferring a place shown on one map to that on another is that it must be the same place on both. Whether the scales of either or both of our maps are accurate or inaccurate, the identity of the place that is located on both is the “independent check.”

Your convoluted method fails this check.

This, again, is yet another proof of how we can know with certainty you are in error.

A reconstruction using your erroneous model.

1. The Zodiac decides that, for some unfathomable reason, he is going to set up his bomb in Neary Quarry, far away from any ability to target a school bus (but that’s a separate issue);
2. The Zodiac performs a measurement on some or other accurate map of his own, not the Phillips, and uses its scale to determine that the distance of Neary from Mount Diablo is around 38.4 miles;
3. The Zodiac, assuming the printed scale on the Phillips 66 map of 6.4 miles to the inch is correct, runs the calculation and determines that the distance from Mount Diablo of Neary Quarry on the Phillips should be 6 inches;
4. As an “independent check,” The Zodiac measures the distance of Neary Quarry from Mount Diablo on the Phillips 66 and finds, to his surprise, that it is only 5.45 inches;
5. The Zodiac now knows that the printed scale on the Phillips 66 is in error, significantly so, and therefore cannot be used as he had set out to use it;
6. Ultimately, he realizes—if he hadn’t already —that he doesn’t need to then start working out what the correct scale is, as had been his concern at first. He can simply encode 5.45 inches and be done with it.

What he cannot do is just carry on and encode the “6 inches” anyway and suppose that we will be able to follow him down this route of madness.