Davis Ranger: Going the Distance
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- เผยแพร่เมื่อ 5 ต.ค. 2023
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NOTE: in the video I accidentally state that a furlong is 220 feet when it is actually 220 yards.
Introduced by the Davis Instrument Corporation in 1969, the Davis Ranger is a type of Stadimeter, an instrument which uses the known size of an object to calculate its distance. It is one of many different designs for optical rangefinders which have been developed over the last 200 years.
SOURCES:
patents.google.com/patent/US8...
patents.google.com/patent/US4...
www.skipjackmarinegallery.com...
www.britannica.com/biography/...
www.worthpoint.com/worthopedi...
www.navalgazing.net/Rangefinding
patents.google.com/patent/US3...
www.prc68.com/I/RF.shtml
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I like how this is totally passive. There's no laser to alert your neighbor that you are calculating artillery coordinates on his house.
13Fs are trained to just pick an object near the target to laze if laser detection equipment is suspected.
Quick and dirty. But it works.
@@johnharker7194Picking a nearby obviously passive target makes sense, especially since a laser beam is narrower than radar.
I don't know if these are in common use any more, but civilian LIDAR detectors for speed traps at least used to work, but not as well as RADAR detectors. The laser detectors must pick up weak reflections from objects and other traffic. Of course police get training too, mainly to leave the beam off until the target is nearby, you can't detect what isn't there.
This brings me back to my early Coast Guard days when we had one of these on the boat.
Your explanation of how it works is way easier than the manual.
FWIW: For some reason I seem to recall seeing one of these _gizmos_ many years ago, although I cannot recall exactly when and where.
I was in the USCG, and for about the first 1 1/2 years was stationed aboard a Cutter. I wonder if that is what I am remembering?
@@Allan_aka_RocKITEman sounds like it. We had it on a cutter. The captain said it was used when he started (which would have been in the 70’s or early 80’s.
Really? A fraudulent layman's explanation is better than the engineers manual? Oh wait you said coast guard, so yeah that tracks. RETARD!!
Did you keep it next to the tampon dispenser on your little coast guard boat?
11:45: Thank you so much for giving me the context that I was missing in regards to dazzle camouflage. I never put two and two together that it was to confuse German U boats, or how it worked.
Underrated channel. Cheers for the great content.
I made a simple stadiametric telemeter out of receipt paper at work, it unduly and (especially in the case of my college-educated coworkers) disappointingly confused everybody. At least some of them had fun with it for a few minutes.
Similarly, I've found a selfie 🤳 stick with 1 yd extension tubes & 4" handle = 1 meter total. So I've attached a 10cm ruler, for direct reading mils. Not unlike a Coast Artillery "rake" (1 m handle, teeth 1cm spacing iirc?) from 100 years ago - used to measure misses' deflection.
@@BillRicker Beautiful idea
Ahh why am I not surprised. God bless the educational system
Speedy recovery and a pleasant vacation! Thank you so much for sharing these fascinating subjects!
So happy tour channel is starting to get the attention it deserves.
This channel is amazing! It’s similar to forgotten weapons but about everything. You don’t just talk about the history but the design philosophy and the science behind whatever associated discipline there is. Thank you for all your effort - I have subscribed.
My dad had a camera in the 60's that had a focus system with a small square in the middle of the viewfinder. You had to align the ghost image with the subject in the viewfinder on top of each other. Your range finder reminded me of that. I was surprised to see in the pictures that the adjustment was side by side instead of on top of each other.
Thanks for your work making this video.
Love your channel, man. After I learned basic trigonometry the operating principals of various range finders and navigational tools like the sextant became very interesting to me and helped me in various pursuits- mostly celestial navigation and long range shooting. I learned to use a sextant before the usage of GPS was demilitarized; I still find it pretty damn incredible that having an accurate chronograph and sextant along with the mathmatical knowledge to use the data you gather with them can let you position yourself on the planet with an accuracy of ~600 meters.
Which segue's to my question:
I know that they can be quite difficult to aquire, but do you plan on making a video on the Curta mechanical calculator? I believe that such a video would help give your channel the exposure that it richly deserves.
Maths is an extremely powerful tool and the basis of science for a reason, GPS is also just based on math but in this case it's based on the math of General Relativity.
I think the sr71 and appolo missions used a navigation system that was similar to looking at stars with sextant
Bell and Howell made cameras in the 60/70s with a focus matic system.You would aim the camera at the base if the subject,push a button, and a weight would swing the lens into focus at the calculated distance.
That is brilliantly simple, and pretty effective probably.
@@ClimateScepticSceptic-ub2rg It worked ok on level ground and with semi-wide angle lenses, handy on a simple viewfinder camera.
Such an under rated channel. The production quality to sub ratio is insane!
Great flying overview og a wide variety of related instruments! The Coast Artillery vertical-baseline Depression Position Finder (DPF) was the "Total Station" of its day since it read Range and Azimuth simultaneously.
I am from Jersey in the Channel Islands. During the Occupation, from 1940 to 1945, fortifications were built on the Island. Including installations for 3.4, and 5 meter stereoscopic rangs finders.
Hi fellow countryman
Glad simon sent me, even your early videos are high quality. Severely underappreciated channel!
Amazing as always. I’m glad Simon gave you the credit where due and hope you see an appropriate subscriber boost.
Simon of what channel?
@@benholroyd5221Simon Whistler of... well, far too many channels. "Today I found out" is one of them, they're all cross linked.
@@jandl1jph766 oh him. Yes he is everywhere.
@@benholroyd5221 The shout out was in Today I Found Out, but Simon is the presenter for about a 10th of all TH-cam channels it seems.
th-cam.com/video/Qgr-tNp_WZk/w-d-xo.htmlsi=uNdl-yEObAAcYswj
Thank you for such interesting and timeless videos!
Enjoy your holiday and feel better
I went all the distance^^
Thanks for this video. In War Thunder, tanks and ships have these sometimes good visible rangefinders, now i know how they worked in real life!
In the airforce we learned the manual way.
If you know the size of something, you can hold out your thumb and close one eye then the other. Count number of repetitions and multiply by 10 and you got the distance. We called it the "Rangefinger".
Absolutely love this channel. Subscribed!
These old inventions are cool because they are all based on mechanics that the average person can understand. I saw the phenomenon of "ghost image" and its relationship with distance as a child, when I was playing with a window that has two movable panes :) Today's inventions are based on electronics and the average person has no chance of understanding how they work.
Nice jacket, very well made. Great video as always. Thanks for sharing such great information
Very interesting and comprehensive. Thank you
Please get well soon
Hes not on his death bed he didnt mention his sniffle I wouldnt notice 😂
German war ships were feared for their gunnery accuracy
Great videos. Can you do a video on the escape and evasion gear that was smuggled into the pow allies ?
This is excellent Gilles!
Fantastico !!! This item and the video !!!
Fantastic, really well explained learnt a lot thank you
Hi Gilles; I am very much enjoying your work! You have an amazing collection of interesting items and topics some of which are new to me. Unfortunately, this video (on the Davis Ranger) has a clanger in it. A furlong is 220 YARDS, not 220 feet as you state at 1:10. You are correct that a furlong is 1/8 of a statute mile and if you multiply 220 by 8 you get 1,760, not 5,280. I know it is darn hard to produce the sort of videos you are making and to get every little detail correct so don't let this slip up concern you too much but if you ever update the video this would be a glitch to fix. I hope you get over the cold soon... Regards... Vince
I was wondering about this! 220 feet is 1/24 of a mile, not 1/8!
Your vids are fantastic...subscribed! You have a great way of laying it all out when it comes to the history and operation of some of the most obscure and fascinating devices. I have had a few of these Davis stadimeters. Unfortunately, the plastics didn't age well and they no longer work.
One small edit at 1:09: A furlong is 220 yards, not feet.
Wow! I understand the concept. Id never be able to build something like this though. Don't really know how this got into my suggestions. I like it.
Ive got a PSO-1. It work pretty well I must say! I also have a paired soviet 20x spotting scope with the same system. My favorite part is the hidden giant screw in the mount meant to be driven into a handy tree.
Used to have one of these in a SLR camera viewfinder for focussing
Great episode. Thanks. Oh, Davis is still around!
Another lovely chapter of the Encyclopedia of Engineering Curios.
very interesting.....thanks so much...
7:45 The optical rangefinder of the German Leopard 1 tanks could be operated in both modes.
It would be neat to have a friend or relative like this.
Excellent 😎👍
A ‘mil’ as used by the military is defined as the angle subtended by 1m at 1 km. however that should be 6280 mils in a circle (2 x pi x 1000) whereas in fact military compasses approximate this as 6400 mils to the circle
For more information on history of early range finding in a naval context I can strongly reccomend the book Naval Firepower by Norman Friedman
and the american system was "If you're in optical distance you're too close"
How dare you invade the privacy of my deck chairs? 😮 😝
Thank you. Keep working, good luck.
Very interesting thanks
You need way more subscribers sir, by 2 orders of magnitude at least
13:02 - that's actually a civilian reticle. The military one used the stadia at 1,75 m base.
I found a Ranging rangefinder at a Goodwill in Phoenix once. Kind of annoying to use but in a fun way. 😄😄
Fascinating. I just bought one on eBay.
Another related item (and one I think worthy of its own video) is the American ART-II riflescope from the Korean war era. A variable-magnification scope with rangefinding reticle, mated to a base that allowed the front of the scope to pivot vertically, and the rear to raise or lower based on an offset cam slaved to the magnification-adjustment knob. Fixing the target in the reticle thus eliminated the need to elevate crosshairs, while also providing range dope, (i.e. if your scope magnification is at 7X, the target is 700 yards out. (Yes, back then it was "yards")). 😂
Just found your channel through Simon Whistler. He also recommended your book, "Calling All Stations" and I absolutely loved it. Can't wait for the 2nd book if you're still writing a series.
I hope the Depression Range Finder is getting counselling.
give my best wishes to your voice.
I'm amazed at how smart people were that long ago
8:11 I spit my coffee moment😂😂
Enjoyed the episode. Programmatic question.. when you put the suit jacket on, do you bother with the slacks, even if they don't show up on camera? I think I would probably just wear shorts.
I wear slacks, but not necessarily matching ones.
@@CanadianMacGyverI’m sure unmatched attire will dazzle the enemy and make targeting difficult. 😵💫
A furlong is 220 yards, not 220 feet. A stadion is around 210 yards, not 210 feet. That would make a Greek pous about equal to one modern foot.
@OurOwnDevices, "feet" please include metric unit measurements in the video.
I have a friend that works for Davis Instruments, Weather division. I'll ask if they still carry that product. They moved from Oakland to the next city, San Leandro. I don't know if they just did not change the label (quite possible) or if yours is an old product no longer made. If they still make them I want one. We are both sailors so it would be a good navigation tool.
I talked to my friend. Turns out Davis was not in Oakland but started in San Leandro, moved to Hayward. He said that they don't make them anymore and thinks the stores they had were donated to the Army in one of the Gulf Wars. Too bad. He will poke around, sometimes he finds forgotten examples hiding here or there.
Some phones with dual cameras do the same thing as superimposed image alignment rangefinders do
❤
What I don’t understand about these surveying devices- and I wish somebody here would explain this to me- is that this technique (and any other technique that measures distance in the open air) only gives you distance from Point A to Point B “as the crow flies”. It doesn’t give you the “practical” distance that you’d have to walk over the ground to actually get from Point A to Point B.
Can anybody explain how this is accounted for?
Thank - you . ( 2023 / Nov / 15 )
Very interesting.
Just for the record, though, a furlong is 220 yards (or 10 chains or 40 rods). Also, approximately 200 meters.
Sorry to be "that guy." Bonus to make up for it, though: a lot of streets used to be in multiples of rods & chains. So there are lots of old main streets 66' wide.
4:04 this pic shows a periscope stadimeter
Uh-oh. Sir, the depression range finder is reading zero.
He's going the distance....
Why not just use a sextant? It is sort of silly to mess around with all the optical Rube Goldberg stuff when a sextant is already extremely accurate means of measuring angles.
1:11 Nope. A furlong is 220 Yards. That is 660 feet. 220 feet would be 1/24 of a mile.
Watching this, I had the same correction to make. I multiplied 220 by 8, and I only got 1,760 instead of 5,280. I recognized 1,760 as the number of yards in a mile and realized that a furlong was 660 ft, or 220 yards. It had always bugged me that it was 5,280 ft to a mile, or 1,760 yards, until I learned of a practically abandoned intermediate measure, the chain. A chain being 66 ft, or 22 yards; and 10 chains to a furlong, and 8 furlongs (or 80 chains) to a mile, it all seemed a bit less arbitrary (though definitely still quite arbitrary compared to metric (though my mind definitely grasps miles better than km).
One of the interesting things about the chain is that it was mostly used by surveyors, and because of that, most residential house lots in the U.S. are 66 ft wide. Also an acre is 1 chain by 1 furlong (which hurt my brain, thinking it should be a nice square measure for area). Most residential lots are quarter acre lots, with a quarter of 660 ft of a furlong being 165 ft, which is often about the depth of a residential lot (often with street easements eating into that a bit).
I have a WW1 pocket range finder that will easily fit inside a matchbox.
@01:14 - No. 1760 YARDS per mile, of which an eighth is 660 FEET, or 220 yards.
Oopsie-Daisie.
I have a Bushnell laser range finder that looks like a binocular telescope. It can tell the range out to 1000 yards and is handy for archery or rifle use. It cost around $100 when I bought it, but now they are much smaller, but they cost $600.
2:33 we still use this
Have you ever done a WWii bomb sight?
👍🏼👍🏼👍🏼👍🏼👍🏼
Nice kukri in the back tho, seems to be a MK2. Am i Right?
Excessive eyestrain you say?
The British have carrots!
@ 1:10 how can 220 feet be 1/8 of a statute mile? maybe you meant to say 220 yards.
Can you not set it to zero and align it exactly?
Then you don't need to know the length at all.
Your videos are very informative, but it would be better if you used metric system.
Please collab with forgotten weapons my brother
220 feet is 1/ 24th of a mile.
A furlong is 220 yards, not 220 feet.
We should get some small mirrors and try to 3d print one of these. It is too useful a device to let fade from history. Soldiers in Ukraine could use it to confirm the range to tanks on a steep hill, because if you laser range a modern tank the laser warning receiver onboard will automatically traverse the turret to you and fire a shell from the autoloader.
Mm so drones with laser pointers can wind up Ruski tanks
A furlong actually 220 yards, not feet or 660 feet.
Gilles, please say you name more slowly. I can understand a good deal of Quebecois but until I saw it written I had no idea.
The chairs are NOT 4ft.
In future could you also include metric values?
I don't suppose you're related to the astronomer?
I really like your channel. However, if a furlong is 220 ft., my horse can run 90 mph.
stay-dee-om-eter not stad-eo-meter. like ther-mom-eter instead of ther-mo- me-ter
I golf. Im kinda good at finding range with my mark 1 peeps. I want to find an optical rangefinder I can use on the golf course. 7 foot flags, less than 500 yards etc. My goal is to bluff my competitors with science while I slip my hand into their back pocket and take their $ with wagers.
lil help pls.
I thought rangefinders were a big no-no on a golf course. I know they are not allowed in tournament play. Any golfers out there who care to comment?
A furlong is 220 yards not feet....
Sounds kinda like the surface is flat.
Did you not hear him say how they needed to correct for curvature?
@@bob_the_bomb4508 yeah, it's the only part of the video I watched, actually. I doneeven know what that doodad does.
Metric dude, please