290. Gary Hamilton, CPG on System Cross-Vent Tenon Extensions


Jonathan Fields, Josh Burgess and Glen Whelan
at the new Deansgrange factory in County Dublin

So your minds don’t turn to mush over the 4th weekend I’ve invited Gary Hamilton to share his thoughts on System Cross-Vent tenon extensions. With his applied science and engineering background, he understands and can explain “Systemology” better than anyone I’ve met.

Gary: I wish Charles Peterson had keep a detailed notebook on his design thoughts and theory, etc.  That sure would have helped!  I also hope (as a CPG) none of the thoughts below are taken as blasphemy, I just tend to think about things and the concept of “how and why” always tend to work their way into the thought process.  After all, I do smoke the “Thinking Man’s Pipe”!

In PPN #208 Mark mentioned that the screw-in tenon extension first appeared in 1891 and was associated with the stems for the Deluxe and Premier System pipes [see also PPN #154].  When I look at the 1896 catalog, for the stems that have been identified as the ones having the bone extensions, the illustrations do not show any semblance of cross vents being present.  Even with a 120 degree separation for 3 cross vents, one could have easily been illustrated.  But I do not see one.

Mark, is there definitive evidence that the cross vents were part of the initial offering of the screw in bone tenon extension in 1891?  What about original patent drawing filings, do any Patent drawings show the presence of the cross vents – or was the tenon extension not a part of patent filings?  I believe that later catalogs like the 1906 used actual photographs of the pipes, and not hand drawn illustrations.  Do any of these later catalogs show the cross vents in the screw-in type tenon extension?  It just seems odd that with as much hand-drawn detail that is present in the 1896 catalog illustrations, that the cross vents were omitted, assuming that they were present at the time to have been illustrated.

The only illustration of tenons in the 1906 catalog (also notice the great explanation of stem nomenclature).

Mark: No, I don’t see any cross vents in the 1896 nor the 1906 or 1937 catalogs. The patent for the System that Charles Peterson took out don’t mention the tenon extensions. More’s the pity.

The 1890 patent wasn’t entered in the US until 1894. Here is the complete document.

Gary: Here is where my theory starts, and I’ve attached some illustrations to use in the discussion (Figures 1-6). My basic premise is that the original bone tenon extension did not have cross vents and that they came along at some later date.  But when?

Let’s start with the following “givens” for the basis of my premise:

  1. The screw-in bone tenon extension (later aluminum) extends past (below) the draft hole in the mortise.

Fig. 6

  1. The molded tenon extensions, for the most part, do not extend below the draft hole in the mortise (the 309 in Gig. 6 is a good illustration of this).
  2. The molded tenon extensions do not exhibit cross vent drillings.
  3. Basic diameter of the draft hole through the tenon extension is about 5mm, and the start of the tapered bore of the stem is the same at about 5mm. This gives a cross section area of 19.6 square millimeters in the tenon extension bore.

A slender bone tenon extension (unsmoked) from a c. 1955 Premier 264 (n.b.: all straight Premier, Deluxe, London & Dublins at this time used this type of slender bone cross-vent tenon extension)

  1. For the 1955 bone tenon extension example you give, the cross vents measure about 2mm in diameter; the combined cross sectional area for all 3 vents is 9.4 square millimeters; or about ½ the cross sectional area of the bore through the bone tenon.
  2. The cross sectional area of the 3 cross vents, being about ½ the cross sectional area of the bore through the extension, is suitable to create a siphon / vacuum break point. More about this later.

An aluminum cross-vent tenon extension from a Late Republic Deluxe System

  1. The aluminum extension example has smaller cross vents and area. Using a 1.5mm diameter cross vent, the combined area of the 3 vents is only 5.3 square millimeters – a lot less than the bone tenon extension, and less effective as a siphon break.
  2. A fluid will preferentially follow the path of least resistance; for our discussion air (smoke) being capable of taking the shape of its container meets the definition of a fluid.
  3. As smoking progresses, condensation occurs and the System reservoir will continue to fill and accumulate condensate over time, unless it is swabbed out or otherwise emptied.

Before continuing with my thoughts on the cross vents, I’d like to take a brief excursion into the mystique of the Patent-era System, circa 1896.  In the 1896 Catalog reprint on page 14 there is an enlightening proclamation from Kapp & Peterson discussing the Improved Peterson’s Patent which leads the reader to the statement that: “the moisture in the pipe and wetting of the tobacco is only saliva coming from the mouth, accumulating in the stem, and from the stem to the bowl and therefore moistening the tobacco.”

In a later paragraph of the Patent advertisement the following statement is made: “A great many smokers say ‘I do not expectorate into my pipe.’  That may be so; but they should not forget that their breath with which they draw the smoke, contains moisture in itself, which deposits in the stem, and is therefore drawn back to the mouth.” These are interesting statements from the 1896 catalog.  As modern-day pipe smokers, what do we think of these thoughts and statements from 1896?

Let me first state that I’ve smoked a Peterson System for quite a while. I have rarely had any issues with the dreaded pipe gurgle in a Peterson System pipe. As advertised, they do provide a dry smoke.  I’ve smoked nearly entire bowls in a System without consideration of the need of a single pipe cleaner to swab up any moisture.  I cannot say that of non-system pipes.  But what about the 1896 Catalog patent statement that “the moisture in the pipe and wetting of tobacco is only saliva coming from the mouth”?  At this point a bit of my engineering background starts to kick in, along with my usual questioning curiosity:

What about the by-products of organic fuel combustion and the relative humidity of the air that provides the oxidant in the process of keeping the tobacco smoldering nicely in our favorite Peterson System pipe?  Charles Peterson made no reference of these potential contributors as to being a possible source of moisture formation in that Patent-era document explanation, only saliva.  Ok, call me a bit skeptical at this point, even though the Patent era document is interestingly worded.  I know from a little chemistry that at least two by-products of organic fueled combustion are carbon dioxide and water.  So maybe besides saliva, there is consideration of moisture formation from other sources.

In the Patent document explanation, Mr. Peterson further elaborates that a smoker’s breath, in which they draw the smoke, contains moisture in itself, which deposits in the stem and is therefore drawn back into the mouth.  Well perhaps this is so.  For full disclosure I must acknowledge that I am not much of a pipe clencher. I find it a bit awkward, and I don’t like divots in my stems.  But for those who do clench, I can see the potential for some formation of moisture in the stem due to one’s breath.  For me though, when I bring the stem to mouth for a draw, I’m always pulling on the pipe.  In this fashion I just cannot fathom how one’s breath moisture travels down the pipe stem toward the bowl, only to be returned to the smoker’s mouth, as described by Mr. Peterson.  Perhaps in the Patent-era all pipe smokers were clenchers?

Regardless of the source of its formation, we do know through our own experience with System pipes, that the reservoir does collect fluid.  And sometimes rather capacious in quantity!

In the last paragraph of the Improved Peterson’s Patent discussion on page 14, the statement is made that “in our invention it is impossible to draw the saliva back into the mouth as the graduated bore prevents it. . . . the strongest pressure could not draw anything up but pure smoke.”  Time to experiment, albeit with a molded tapered bore stem.  However, I feel that the experiment will be satisfactory in that I’m testing the graduated bore design of the stem, per the Patent discussion, to see if I can draw fluid (saliva in Patent-era speak) through the stem to the mouth.  Will it act like a drinking straw?

Into a glass of water (my substitute for pipe “condensate fluid”) I positioned the stem such that the opening of the bore through the molded tenon extension was about 1/32″ to no more than 1/16″ of an inch below the surface of the water.  Now for a test draw upon the stem.  Using about the same pull as I would when smoking, I quickly received a slug of water right up the stem to the mouth.  The stem functioned exactly like a drinking straw.  This seems a bit contradictory to the Patent statement about being impossible to draw saliva (liquid?) back into the mouth.

Fig. 1

Returning now to my premise on the origination of the cross vents, let’s look at Figure 1.  In this image I’ve illustrated the tenon extension, with the end of same being below the draft hole.  Shown is the air / smoke path from the bowl, through the draft channel and into the tenon extension opening.  Also seen is the initial collection of fluid condensate in the bottom of the reservoir.  In this illustration there are no cross vents present in the tenon extension.

Fig. 2.

As smoking continues (as shown in Figure 2) the formation of condensate fluid continues and the reservoir fills.  Because the end of the tenon extension is below the draft hole channel, I believe it possible that enough fluid could collect such that the entire end opening of the tenon extension becomes slightly submerged into the condensate.  At this point, like in my stem experiment described above, I believe it possible that a small slug of the condensate fluid could be drawn up the stem to the mouth—just like drinking a soda through a straw.

Fig. 3.

Figure 3 shows the same tenon extension configuration, but now with the cross vents included.  Now there are two different flow paths for the smoke to enter into the bore of  the stem.  As smoking continues, the formation of fluid develops as before and collects in the reservoir.  Following the path of least resistance, the main path for smoke to enter the bore of the stem is still through the end of the tenon extension; it is to be expected that some slight volume of smoke enters into the stem bore via the cross vents.  Remember, the cross-sectional area of the tenon extension is twice that of the three cross vents.

Fig. 4.

Figure 4 shows the continuation of reservoir filling as the bowl is smoked, until at some point the reservoir starts to reach capacity and the end of the tenon extension starts to become submerged in fluid.

Fig. 5.

In Figure 5, this submerged condition has occurred, essentially sealing off the end opening of the tenon extension.  At this point the cross vents begin to perform their intended function, essentially as a siphon or vacuum breaker.  Like trying to sip a soda through a straw with a hole in the side of the straw—you won’t get much soda, mostly air.  This, I believe, is the function of the cross vent, to act as a siphon or vacuum breaker so that if collected condensate fluid level becomes too high in the reservoir, it is not sucked up the stem.  My premise is that the use of the original tenon extension without the cross vents eventually led to the sucking of fluid into the stem and mouth, contrary to the prior published writings of the patent advertisements.  At this point in the company’s design history I believe the cross vents were added.

Mark: Based on numerous examples Gary Malmberg and I documented and photographed for the Peterson book, I believe this took place shortly after WWII or the first years of the Early Republic era, probably 1950-1955.

Gary: Going back to the molded tenon extensions, none had cross vents.  If the cross vents served a useful and functional purpose on the screw-in tenon extension, why was this feature not also incorporated into the molded stems?

My guess is is that it was due to the geometry and position of the molded tenon extension when inserted into the mortise.  As noted in one of the givens I listed at the outset, and as illustrated in Figure 6, the end of the molded tenon extension does not extend below the bottom of the draft channel hole.  As such, it is impossible for fluid collected in the reservoir to cover, or slightly submerge the end opening of the tenon extension.  At full reservoir capacity, excess fluid would now begin to gravitate down the draft hole channel and into the bowl, as it does in a non-system pipe.  In this configuration, no fluid will be sucked up the bore of the stem, thus the need for cross vents never developed with the molded tenon extensions.

Mark: Exactly! This happened to me a few years ago. In the transition from the Dublin to the Laudisi era, somehow the drill bit used for the reservoir was changed and some Systems escaped which weren’t drilled properly as the reservoir was very shallow. The result was that it couldn’t accommodate the accumulation of condensate and I experienced the hiss and splash of wet condensate evacuating through the airway into the chamber floor.

While that problem was resolved fairly quickly, it made me look at the reservoirs of older Systems a little more critically. Some, like that in Fig. 6, are quite elaborate, with a three-stage drilling and a tuck in the bottom. Others, like that seen in Fig. 7, were two-stage affairs, but still containing the bottom tuck toward the chamber. Still others, like the 308 (shape 14) are quite massive and appear to be a single, graduated mortise / well.

Fig. 7

In conclusion, two questions for all of us: first, is the screw-in tenon extension more effective than the molded tenon extension? Second, is the cross vent tenon extension more effective than the non-vented extension?

Gary has definitively answered the second question with a “Yes”—the cross-vents allow the smoker of any tobacco confidence that even if the reservoir should fill, the “emergency” cross vents are there.

As to the first question, it seems to me that the answer is “Yes,” but this is only an experiential answer.I am in hopes that Gary will come back and discuss the differences between molded tenon and tenon extension in the near future. This is a fun questions, especially for those Pete Geeks who wonder whether, in terms of engineering, a Premier or Deluxe is worth the expenditure.



Gary: So, one may ask how I came about the formation of this premise?  Basically by actual events.  In my pipe restoration hobby, I had made an aluminum tenon extension for a Peterson 307 Standard System pipe that I was restoring.  I just wanted one on it, even though not historically accurate.  Using the lathe, I crafted a nice-looking extension, but more is better, right?  I decided to make the extension even a bit longer that what I have observed on other System pipes, my thinking being that more length of aluminum equaled more contact time with the smoke and more opportunity to condense out additional moisture from the smoke. I decided not to include the cross vents.

My oversight was that the longer length tenon extension reached almost to the bottom of the reservoir when the stem was seated.  It did not take too long smoking that first bowl to figure out I had effectively made a drinking straw!  After a few measurements, I trimmed off a portion of the extension and all seems to be well for the time being (and I periodically swab out the reservoir, just in case).  Maybe one day I’ll think about adding the cross vents, but it was this episode that made me connect the dots about the function of the cross vents.  I wonder if Charles Peterson had the same thing happen to him?






A J. T. Cooke Chubby Dublin with Hot Rod custom-poured acrylic stem

I recently published an entry in Pipedia on J. T. Cooke, my favorite artisan carver and in the opinion of many hobbyists the world’s greatest sandblaster . I was made a Doctor of Pipes by the Chicago Pipe Collectors Club last year, and one of the purposes of this organization is to bring recognition to those in either the trade or the hobby. It was an honor and privilege for me to nominate Jim and I was delighted when he won this year. He has richly deserved this recognition for a number of years for his unending pursuit of the finest sandblasted and engineered pipes.




Continue Reading290. Gary Hamilton, CPG on System Cross-Vent Tenon Extensions