Antique W. & L. E. Gurley Wye Level Questions

Recently acquired this antique W. & L. E. Gurley Wye Level, with two tripods and a faded elevation rod, mostly as a curio but I might also try to sight some levels for landscaping.

A Wye Level is an obsolete surveyor's instrument which requires that the telescope be removed from the fork and swapped end-for-end to take a back sight. (Contrast this with a Dumpy Level, where the telescope is permanently affixed to the base.)

The rectangular aluminum base is part of the carrying case. (Somebody wrote "EYE" at one end with a Kiel crayon.)

The wooden cylinder on the base carries the sun shade (which is not original) and also has some holes of different sizes that look like they were meant to carry some small tools. There is also a non-removeable piano wire protruding from this wooden cylinder.

Q1: Can anyone comment upon this cylindrical wooden accessory carrier? What am I missing?

The level vial is A-OK.

Looking through the telescope, I can bring the intact crosshairs into fine focus with the knob on the back, but thus far I have not figured out how to adjust the "distant" focus to sharpness. I would think that because the instrument has crosshairs, there must be two adjustments so that the target and the crosshairs can be simultaneously in focus.

Q2: Is the objective, which is on a slide tube, the adjustment for focusing the target?

Q3: There are four fillister head ("cheeseheaded" to our British friends) at 90 degree intervals around the telescope barrel. These have no slots, but rather traverse holes for a miniature tommy bar. I presume these are some sort of a "do not touch" adjustment, possibly for the crosshairs? Or, what?

Q4: There are fine threads at the eyepiece end. Am I correct in thinking these are for a non-essential eyecup, rather than a missing lens?

It's not in the greatest condition; there's a lot of bare brass showing where the black wrinkle paint has flaked off. But, I bought it as an educational curio, not as a museum piece.

<ON EDIT:> I'm having difficultly uploading the photos due to DSL troubles. Will try again later or tomorrow.<END EDIT:>
John Ruth

There might be some info in this link that may help...

Full text of "Gurley manual of surveying instruments .."

Brian

SouthBendModel34 --

A wye level has a vertical (aka azimuth) axis, which allows target-to-target repointing exactly as does a dumpy level, automatic level, engineer's transit, and theodolite . . . there's NO need to reverse the telescope in the wyes between backsight and foresight.

There should be focus adjustments for the occular (eyepiece) and objective lens. The occular lens system is, in essence, a microscope that magnifies a real image cast by the objective lens system on the plane of the reticle (crosshair). There should be two focus knobs on the side of the telescope, one to focus the occular on the plane of the reticle, the other to focus the real image created by the objective on the plane of the reticle. (See first photo in link: Gurley Engineers' Wye Level )

The objective focus knob moves the objective lens housing on the barrel of the telescope, as you suspect.

Many survey-instrument telescopes of the era have two or more sets of four radial screws, with one to adjust the reticle within the telescope barrel, and a second to adjust the occular microscope pointing so that the centered-in-telescope reticle is in the center of the microscope field of view. Looking at the wye level in the link, I'm going to guess that the reticle-adjusting screws are concealed within the ring-around-the-barrel just above the left end of the cutout in the vial carrier.

Wye levels are more costly to manufacture than dumpy levels, and have more potential sources of instrumental error, so they passed from favor. The wye level does have one real advantage over the dumpy levels and automatic levels, which is that the all adjustments can be made by reversal. The reticle can be adjusted by rotational reversal of the telescope in the wyes AROUND THE TELESCOPE BARREL, the level vial adjusted by reversal of the telescope in the wyes, and the height of the adjustable wye by reversal of a) end-to-end reversal of the telescope in the wyes AND 180 degree rotation of the telescope carrier about the vertical axis.

Hope this helps answer your questions; post back with any additional questions you might have, and I'll try to answer 'em.

John

As for tools that came with it, I would guess that there would be a spanner wrench and a magnification glass.

John:

Typically, in the wooden carrying case for a transit or level, there will be a round wooden "plug" fixed to some part of the interior of the case. A "sunshade" made of thin tubular brass or aluminum and coated with a matte black finish is stored on this wooden plug when the instrument is in the case.

A magnification glass is usually found with an instrument such as a transit, where a magnifier may be needed to read the vernier plates. On an instrument like a wye level (and my memory of this sort of instrument is kind of rusty), there are no scales and no vernier plates (I could be mistaken here), so no magnifier is needed.

Different surveying instrument makers used different tools for servicing and adjustment. Often, the screws to adjust an instrument were made with a hole cross drilled in the head. These take a "pin spanner", or one can be turned from a piece of drill rod.

When the instrument was new, it had not only the sun shade, but a metal lens cap. There may also have been a fine camel's hair brush and a pad of lens tissue for cleaning the lenses of the instrument.

For focussing most of the old traditional surveying instruments, there are two focussing knobs. There is usually a knurled brass knob coming off the top of the 'scope at the 12:00 position. This focuses the image. Turning the eyepiece will focus the reticle (crosshairs). I took surveying in college as a civil engineering elective in the summer of 1972 and spent two weeks in surveying camp. We used the basic instruments- dumpy level, wye level, engineer transit and then moved up to the "three wire level" and the Wild T-2 theodolite. It's been many years since I used a wye level, as once I got into the industry, I used an "engineer transit" for nearly all layout and surveying that I did.

I believe the wye level was so named because of the clamps which hold the 'scope. To take a back sight, it is not necessary to dismount the 'scope and turn it end-for-end. Instead, and much easier, the instrument is unlocked from its base and turned about its center. There is usually a thumb screw to lock the instrument from turning about the center ( usually a conical journal with two bearings set vertically that the instrument rotates on).

What John Garner is describing to work an error out of a wye level is akin to what gives the transit its name. Transiting means turning the 'scope over on itself for a back sight.

I am old school, and came up using the basic engineer transits like K & E, Gurley, or Dietzgen. I've seen the evolution in surveying instruments, and the "automatic levels" are really quite a handy instrument to use. Same as the old dumpy or wye levels, just look like a toy next to the classic old wye or dumpy levels. Total Station surveying instruments blow me away, having sweated through surveying camp hacking brush to get a line of sight and sitting up most of the night to do our calculations from what we entered into our "field books" during the days. We were the last class to go thru surveying camp doing the calculations longhand using logarithms. I'd lusted after a classic engineer transit for ages, never quite able to justify owning one. When some discrepancies and questions as to the layout of the plots and access drives in our congregation's cemetery arose, I suddenly found my justification for a transit. My wife and I are half of the cemetery committee, and I have found myself "stepping off" from an approximate starting point in the dead of winter to locate a plot for another burial. Looking the matter over in the warm weather, I decided it was time for me to own a transit. Wife agreed, so I found a good Brunson engineer transit on ebay within 80 miles of our home. The seller is also a mechanical engineer, and for 250 bucks, I got a really good transit. I bought a "modern" rod graduated in feet and inches, and we are all set. I found it easier to deal with feet and inches than "engineer's measure" (decimals of a foot).

I like using the stadia lines on the reticle to lay out distances. Using the classic surveying instruments is a nice thing to do. As a young engineer on powerplant construction sites, I often had to take a transit and tripod and head onto the site to establish centerlines or elevations for the pipefitters, ironworkers, boilermakers, or millwrights. I used to put the 'scope in a position so the lens pointed at the compass, lock up all the screws on the instrument and put the tripod and instrument over my shoulder. We used to have a collapsible canvas pail in which we carried our surveying stuff- hubs (square wooden stakes for corners or turning points), laths (regular stakes), flagging, markers, center tacks, plumb, steel tape, hand axe (if we were going out on open ground as in laying out foundations and underground piping runs).

John Ruth and I are in the same relative age group, and both of us are engineers. We are of an age when the classic surveying instruments were what was in common use. We are also of an age when engineering students (if they were civil engineering students) learned the basics of land surveying. I was studying mechanical engineering for my degree, but knew where my career was headed, so took a bunch of civil engineering electives. Surveying was one of the most useful of those electives.

W & L.E. Gurley is in Troy, NY. Alas, while they are still in business, they have not built optical surveying instruments in quite some years. On two hydroelectric powerplants on the Mohawk River, the 1920's stream gauging instrumentation was built by W & LE Gurley and included water level recorders using drums with plotting paper and some fine gearing. These instruments were scrapped when those plants were modernized around 1989-91.

Gurley had to have been one of the more prolific manufacturers of surveying instruments. They have not made optical surveying instruments in maybe 40 years or more, but plenty of their transits seem to turn up for sale. Interestingly, when I was looking to buy a good used transit, the Gurley and the K & E instruments were going for higher prices. I was leery of buying a surveying instrument from someone who liquidated estates or cleaned out houses, and a lot of the instruments on ebay looked like they had been knocked around.

The wye level is a real classic as surveying instruments go. Shooting grades with it will be a nice exercise. It is common sense and simple addition or subtraction. Levelling the instrument is something to practice. Again, it is common sense. One thing all novices learn in a hurry is never to let all the levelling screws go loose. With thumb and forefinger of each hand on levelling screws on opposite sides of the instrument, the levelling of the instrument is done. Another lesson the professors and old surveyor at camp hammered into everyone was to treat the instruments with care and never to apply any more force to a screw or adjustment than was needed, just running the levelling screws up "nice and snug". The other thing the professors and old surveyors hammered into everyone was to watch where we walked and to pick our feet up as in every summer surveying camp class, at least one student would tangle a foot in a tripod leg with effects ranging from simply making any readings on the instrument suspect to kicking over the instrument. I always stand with my legs spread and well back from the tripod when I am taking a sight with a surveying instrument, kind of instinct or automatic at this point in my life.

When I take out the transit to shoot line and grade, I get comments from younger men to the effect that they have some handy laser. I suppose the new lasers are quite good, but I have never used one. Shooting line and grade with a "real" surveying instrument is what I am used to doing. Now all John Ruth needs is a "rod person" (can't say "rod and chainman" as the old surveyors did) and a surveyor's field book (sometimes set up specifically as a "level book").

Forgot to mention that the screws with cross-drilled filister heads are called "capstan screws", they are pretty much used only as adjustment screws, and are turned with a "pin wrench".

Conceptually-similar "capstan nuts" were also used, most commonly for adjusting level-vial housings.

The pin wrenches supplied with the instruments were commonly made of larger stock having ends swaged to fit the screw-head and nut holes, and were extraordinarily inclined to get lost. Using a pin of a smaller-than-hole diameter as a substitute was common, and is a superb way to damage the screw heads / nuts, and substituting a hex key is probably an even better way to damage the screw heads / nuts.

The best improvised pin wrenches I've found are drill blanks of whatever size it takes to fill the hole. In the absence of drill blanks, twist-drill shanks will work . . . but it's worthwhile to shrink shrink tubing over the flutes and tip of the drill.

Wye Level Pictures

Here, for your viewing pleasure, are some snapshots I took of my Wye Level:



I want to thank everyone who replied! After reading the replies, I was more confident about trying the various adjustments. Yes, one can unlock it and rotate it 180 degrees around the vertical axis to take back sights; it might have taken me quite a bit of cautious exploration before I discovered that lock.

I've not yet mounted it on one of the tripods.

John Garner's description of the tools helps to understand the storage holes in the wooden spigot that carries the sunshade. Joe Michaels mention of lens tissue may explain the now-bent piano wire sticking up from the spigot - it's probably a "spindle" for storing lens wipes. (I envision that the tissues are impaled on the wire to hold them from going astray.)

Where would the serial number be on an instrument of this type?

Thanks Again!
John Ruth