A couple of years ago I reported I had acquired a T4 and through a couple of posts reported on my learning curve about this instrument and some of its amazing features and capabilities.
I now have more to report. There was one piece that was missing from mine - a set of Horrebow-Talcott levels that are used in one of the methods of precise positioning. My quest for a set took me on a world wide search, but recently proved successful as I'll describe here.
I knew that I was going to have some difficulties because of a particular feature of my T4. Mine turns out to be the 34th T4 ever made and a couple of the first production runs had a method of mounting the levels that changed with later production. Here's a pic of my mount:
Here's a picture of the later mounts. You can clearly see the differences:
So at any rate, my quest for a set of Horrebow-Talcott levels (along with another hanging level) finally ended a month ago when this arrived from Ireland (Thanks, John!). And as a side note, DHL overnight service from Ireland to the middle of no where in Virginia actually works!
But, before I could use them I had to get a mounting bracket made that they would sit on without making any changes to the existing T4 mount. Here's what a friend in PA came up with (Thanks, Bob!):
And here's a picture of the new levels mounted:
So, now its on to my next phase of education and figure out just how these things are used for determining latitude and longitude.
Some people say I'm just a little strange and I freely admit that all my screws are not quite tight, but this stuff is fun!
That's cool Dave. I'm glad you found your parts.
Keeping old instruments and machines serviceable is a noble hobby. I call it "Keeping the Love Alive". What use is a hunk of metal if it doesn't work or nobody knows to use it?
All the time and energy and sweat that people put into an instrument's development needs to be preserved. Their quest was for a higher level of precision was achieved.
What better way of acknowledging their accomplishment by keeping it serviceable and knowing how to use it properly.
"Keeping the Love Alive!" B-)
Awesome pictures Dave. Thanks for sharing.
One of these days I hope to make it to your neck of the woods.
That is awesome.
What an instrument. 🙂
Grantley D Leith
South Australia
FWIW,
There is a nice intro to geodetic astronomy lecture notes available from UNB at
http://www2.unb.ca/gge/Pubs/LN49.pdf
Too bad it has fallen from most geodesy curricula.
Thank you!
That along with a couple other texts will give me just a little serious reading and study to work on.
Dave,
I may never touch or even see that theodolite in person, but I sure am grateful that you are taking the pains to do that. I don't want to imagine a world where these treasures are no longer in existence or no one knows how to use them.
Dave,
I used a T-4 while I served in the Air Force, Geodetic Survey Sq. later to become the Defense Mapping Agency.
The time frame was 1969-1975, then again in 1991-1993.
We used the Sertnoch method for Latitude, the powers to be drop the Hallburow Talcott Method in 1968, this method used equatorial stars, a real pain, especially when you dumped your bubbles.
Have you found an Astro Amplifier?, this thing connected everything together for time, chronograph, sidereal clock and WWV.
DMA in the later years affixed a mechanical device to the eyepiece, automated.
During my time each observer had a PE error attach to their profile, this entered into all calculations.
Have fun with this beast, Wild also made a tripod for the instrument. We always used Piers for a better leveling base .:-)
Have Fun,
Doug Elgin, PLS Wy,Co
>Keeping old instruments and machines serviceable is a noble hobby.
And we'll need that capability again if the country/world situation gets to the point we can't or won't afford to maintain GNSS.
I'm aware of the Sternock method. In fact that is part of the problem of finding Horrebow levels because they took levels out of Horrebow for the Sternock assemblies.
Don't have the astro amplifier, etc. Doubt I'll ever find one - but I'm keeping my eyes open.
Yes, using the T4 on a pier was the best way. Tripods are only really good for training. Here's a picture of one I made.
What a cool instrument!!! I know they are big, so, something in a shot to give perspective, at some point, would be a great add.
Since almost everyone knows a T2 (a one-second gun), here's a T2 next to the T4
http://celebrating200years.noaa.gov/theodolites/wild.html
The link above is to an NGS observer (in the early 70's??)
Having been lucky enough to use a T-1, T-2, and T-3 I can't even image how awesome that instrument is!
Thanks for sharing!
T4 for sale only $45,000 (US)
Only $45K US with free FedEx Smart Post shipping to US!
T4 for sale only $45,000 (US)
Hey, following your link, I see Bujor has a SIAGL for sale. Very cool!
T4 for sale only $45,000 (US)
He's been trying to sell that for a couple of years now. Had a price of $35K for a long time. Just recently raised to $45K.
Thanks for that post. I knew they were big! If you need any help printing some niggly little part, hit me up.
I'll keep that in mind.
My next major purchase is going to be a lathe and milling machine so that for my retirement hobby I can get serious into repair and restoration of antique surveying equipment. I already do some, but need the good, precision equipment.
We both know everything on one is machinable, so, cool. I want to pick up a small CNC for metal myself. Just part of the disease, lol
