08:17:10 From Richard Lyon : Here’s the Henry Ravenscroft guy whose slide rule I gave to his student Richard Davis: https://www.newspapers.com/clip/40880129/obituary-for-henry-a-ravenscroft-aged/ 08:25:32 From Fred Astren to Jim Bready(Privately) : Jim, I am not seeing an image for me, Do you get one? Fred 08:34:33 From Curtis Jones : A quick "hello" from San Jose, CA before I'm off to Sunday school. 08:35:35 From Curtis Jones : The "talks" yesterday were terrific! 08:36:12 From David Rance (NL) : "Goeden avond" form David in Holland 08:39:31 From Jerry McCarthy : Goeden avond, miner! :-0 08:39:43 From Jerry McCarthy : Mineer! 08:39:50 From Jerry McCarthy : Hoe gaat het met U? 08:40:09 From David Rance (NL) : prima bedankt! 08:40:26 From Jerry McCarthy : Prima heer, ook! 08:40:35 From Mike Frey to Jim Bready(Privately) : Hi Jim, It is possible to get a copy so I can print my own version? 09:01:14 From Michael J. Vinarcik : That's a bummer! 09:18:52 From Murray Felstead (Ballarat, Australia [ VK3AAI ]) : It's even earlier in Australia than NZ! 09:19:51 From Issy Arieli : Yes 2:19 am in Melbourne 09:24:04 From Tom Frank (KA2CDK) : Does this mean you use different sized sprinkler heads along the length? 09:28:30 From Tom Frank (KA2CDK) : 0.434 would be fresh water. Salt water is a little higher. 09:34:10 From Michael J. Vinarcik : Nicely done! 09:34:25 From Nathan Vinarcik : Thank you for presenting 09:46:03 From Michael J. Vinarcik : My first was an HP28S to help with thermodynamics...divide 2 matrices to solve linear equations. 09:49:01 From Michael J. Vinarcik : Very nice image of your collection. 09:49:28 From Nathan Vinarcik : I'm in awe of their condition. Excellent. 09:50:37 From Robert De Cesaris : This display is well-done. Compact and definitely artistic in an engineering sort of way...... 09:50:51 From Nathan Vinarcik : agreed 09:52:28 From jeff white : Ah but if only the maker of that rule had access to carbon fiber for the stators! 10:04:29 From Robert De Cesaris to Jim Bready(Privately) : Not understanding why the diameter of the spiral rule (which would increase scale length) is not a factor ?? 10:05:13 From Robert De Cesaris to Jim Bready(Privately) : ie Colossus is more accurate than any Fuller 10:05:44 From Richard Juday : Part of the precision is how well the graduations are placed. How were the scale positions calculated, back in the day? 10:06:55 From John Runnels : Perhaps manual calculations with log tables? 10:10:34 From Murray Felstead (Ballarat, Australia [ VK3AAI ]) : Journalists are notorious for failing on significant figues. 10:13:48 From Tom Frank (KA2CDK) : Let’s not forget the K+E N-4096 where they take advantage of the extra length to permit a larger ‘font’ for easier reading with aging eyes. 10:15:11 From David Rance (NL) : For most makers 20 inch/ 50cm models were less than 5% of their total production volumes. 10:15:51 From Jerry McCarthy : Interesting.... 10:16:20 From Michael J. Vinarcik : Wasn't there a REALLY big spherical in use at an observatory or some such for maximum precision? 10:17:01 From Jerry McCarthy : Spherical? That sounds interesting!! 10:19:56 From Michael J. Vinarcik : Can an expert help here? THought it was at an observatory or other scientific establishment. Oddball custom rule. 10:20:04 From Michael J. Vinarcik : 3 feet in diameter or some such. 10:22:23 From Richard Juday : The log-log scales work a different problem than multiplication/division. That is, they work exponential problems. Compound interest, for example -- or decline in radiation intensity throuhh absorbing media. 10:22:57 From Amy Ackerberg-Hastings : I vaguely recall a cylindrical used in astronomy that was much larger than a Thatcher, but I can’t remember where. It’s not in the National Museum of American History collections, for sure. 10:24:34 From Michael J. Vinarcik : I thought it was so big it had to be suspended. 10:25:29 From Bob Adams (Adelaide Australia) : there is a hemmi rule No 200 that is a 16inch rule that had the C and D scales segmented 6 times that equaled a scale length of 96 inches 10:26:28 From Robert De Cesaris to Jim Bready(Privately) : Excellent post presentation sharing I have a half dozen questions but will contact John privately. 10:26:44 From Michael J. Vinarcik : Maybe it was cylindrical instead of spherical... 10:27:32 From Jerry McCarthy : A friend of mine, who was involved in reparations after WW II, "confiscated" a 3-man circular slide rule that had to be wall mounted and needed a ladder for people to use it. I believe that it was for navigational purposes. It was at Farnborough Airport, U.K. I have no idea where it is now :-( . 10:28:17 From Nathan Vinarcik : wow 10:28:24 From francesco basta : My goodness ! That's large ! 10:29:38 From Andries de Man : A number of LOGA’s in the wild http://beeldbank.amsterdam.nl/afbeelding/010163000504 10:37:32 From Mike Frey to Jim Bready(Privately) : And drop the video 10:44:18 From Amy Ackerberg-Hastings : Thanks, Andries; LOGA is probably what my brain was trying to remember. https://americanhistory.si.edu/collections/search/object/nmah_1215054 NMAH also has this very fat rule invented by Elizur Wright: https://americanhistory.si.edu/collections/search/object/nmah_1050982. The “confiscated” rule sounds very impressive! 10:45:30 From wolfgang : I found the shown picture in my MeyerZurCappellen 10:47:47 From Nathan Zeldes : This we saw at the MIT museum in IM2011 10:48:28 From francesco basta : Nice Pic Nathan ! 10:48:48 From Nathan Zeldes : Nice museum, nice display! 10:48:56 From Andries de Man : The Faber Castell welding rule: http://www.rekeninstrumenten.nl/pages%20and%20pictures/27931.jpg 10:49:44 From Jerry McCarthy : All you need on the back :-) 10:52:22 From Piet van Unen : Nico Smallenburg published the book De LOGa Calculators in sept 2004 11:06:21 From Jerry McCarthy : Did he say the size of this Askania Kreisrechenscheibe? Possibly I missed it. 11:06:40 From Jerry McCarthy : OK. Now he says it. 11:09:55 From Fred Astren : Everyone, mute your microphones. 11:12:48 From Richard Juday : I worked with (but not in) the group of folks who analyzed flight video of Challenger's crash, 1986. They tracked the pieces well enough to send vehicles to spots in the Atlantic where to recover the wreckage. Same basic problem and calculations. 11:12:52 From Jerry McCarthy : Flak = Flieger Abwehr Kanonen…. 11:16:23 From Tom Frank (KA2CDK) : When you could smell the explosions, they had your altitude dialed in. 11:22:43 From Richard Juday : In another related problem: a baseball outfielder runs to catch a fly ball. He runs not directly to the impact point to wait there, but instead runs at a constant rate to arrive there at the same time as the ball. What he is doing is, in analog fashion, running in such a fashion that the tangent of the elevation angle is rising at a constant rate. 11:24:17 From Harold Frost : https://drive.google.com/file/d/1jYYNWsm1qIHO_tA66lUlGaHymvz_VK8R/view?usp=sharing 11:28:29 From Mike Frey : Google books link https://www.google.com/books/edition/Graphical_and_Mechanical_Computation/Eh46AQAAMAAJ?hl=en&gbpv=1&printsec=frontcover 11:31:09 From Rob James : One favorite specialty rule for students is the juggler's rule--how long should you take to introduce another ball if you are juggling five balls at a time! 11:31:15 From Rob James : http://www.andtheugly.com/slides/jsr/jsr.html 11:39:19 From Jerry McCarthy : That's one of Colin Tombeur's rules; Peter Hopp mentioned him at the beginning of this meeting. 12:00:38 From Nathan Vinarcik : Thank you. Really interesting. 12:19:42 From Richard Juday : In another interpretation, this is a weighing scale! 12:21:26 From Jerry McCarthy : This is exactly the kind of wacky, special purpose rule that I just love to play with, and try to get to understand. 12:22:07 From edwarddeanbutler : This one is beyond me! 12:22:28 From Rob James : The laser beam must have been the "HP-35" to this rule. 12:23:06 From Richard Juday : Can we make one that takes special relativity corrections into account? 12:23:55 From Nathan Vinarcik : I would buy that. We covered I lightly in Physics 1 and I got tripped up by it. 12:24:17 From Robert De Cesaris to Jim Bready(Privately) : Only 69 as we enter when the action was supposed to start.....bit of a surprise today we seemed to top off around mid 70's 12:24:21 From Nathan Vinarcik : *it 12:26:01 From jeff white : As I recall, the Electronic Distance Meters (EDM) that arrived in the mid 1970s used infrared. It was a bit later that lasers were applied in surveying. 12:26:35 From Jerry McCarthy : Bravo, Señor! 12:26:43 From Nathan Vinarcik : Thank you for presenting. 12:27:09 From Richard Juday : On the topic of precision... LIGO (laser interferometer gravitational observatory, that has measured gravity waves) has a sensitivity of 10^(-21). Compared with the 4 light years to the nearest star, that's a precision of about 0.015 inch. At some kilohertz measurement rate. I can't get my head around that. 12:27:36 From Stefan Heimann : Muy interesante, José! Entiendes japonés? 12:27:57 From Michael Konshak to Jim Bready(Privately) : my laptop bailed. let me in please 12:29:35 From Jerry McCarthy : He probably does now. Most of it is in Katakana, which is method of rendering English into simplified Japanese characters. 12:30:26 From Louis Gotlib : one is on ebay right now: https://www.ebay.com/itm/Fuji-Slide-Rule-Deals-w-Temperature-Sag-Tension-of-Metal-Tape-Measures/154057788006?hash=item23de8f4a66:g:bPEAAOSwr0ReTsdH 12:31:32 From Jerry McCarthy : Only $124.99 :-) . 12:32:37 From Gonzalo Martin : Bravo Jose! 12:33:22 From Michael J. Vinarcik : Go Eagle Eye Fred! 12:33:41 From Nathan Vinarcik : That's a steal of a price. 12:34:16 From Louis Gotlib : not so sure. It looks like an identical one sold earlier in the year for $60 12:34:37 From Michael J. Vinarcik : They're all worth whatever someone will pay! :-) 12:34:58 From Michael J. Vinarcik to Jim Bready(Privately) : Jim: I'm going to reboot. Please watch for me in waiting room. 12:36:30 From Richard Juday : Prism can be mostly taken care of by decentration 12:36:43 From Peter Alfeld : Fuji slide rule sold! 12:37:07 From Louis Gotlib : I wonder I is was posted during this talk? 12:37:21 From Louis Gotlib : oops if it was posted 12:37:35 From Peter Alfeld : probably bought by one of us! 12:38:19 From Jose G. Fernández : Maybe I should get a comision... 12:38:20 From Tom Frank (KA2CDK) : Beat me to it! 12:38:54 From Peter Alfeld : your talk was very interesting Jose 12:39:12 From Nathan Vinarcik : yes 12:39:20 From Louis Gotlib : my experience is that a few more will show up in the next week or so with the hopes of realizing that price 12:40:55 From francesco basta : Bye bye folks, I need to leave. Enjoyed the presentations very much ! Enjoy the auction ! 12:42:52 From Vinarcik : That's very generous! 12:47:45 From Gonzalo Martin : Bye Bye, bonne continuation! 12:51:49 From Stefan Heimann : Good bye friends. The virtual IM was a great thing - may be, it can repeated one year or we can include virtual guests and presenters in future IMs. Thank you to the organizers. 12:56:34 From Nathan Vinarcik : Thank you to the organizers and presenters. I had an amazing time. I hope to see you next year. 12:56:57 From Jerry McCarthy : Bye! 13:00:05 From Klaus Kühn : Thanks for the great IM 2020, best wishes Klaus 14:00:13 From Muriel : I enjoyed the meeting, the presentations and the auction. I was there some decades ago when my Dad bought my first slide rule at an auction. Thank you, Muriel. 14:01:12 From Murray Felstead (Ballarat, Australia [ VK3AAI ]) : Theres a mark one on ebay now for $1300 14:01:58 From Louis Gotlib : balloon pilot slide rule?? 14:02:27 From Murray Felstead (Ballarat, Australia [ VK3AAI ]) : no curta 14:02:50 From Louis Gotlib : oh model one 14:03:20 From John Runnels : Excellent meeting. Well organized, job well done! See you guys in the future. Best wishes. 14:03:41 From Nathan Zeldes : This was a very nice meeting! Thanks to the organizers and see all of you soon, hopefully face to face! 14:03:41 From Will Marchant : Excellent work, Jim! 14:03:43 From Rob James : Great meeting, thanks all! 14:04:04 From Fred Astren : Great meeting, indeed! 14:04:08 From Louis Gotlib : This was a lot of fun, although I do look forward to meeting in person. Thanks for all thee efforts to set it up and make it run so smoothly. 14:04:09 From Bill Reich : Excellent meeting! Really enjoyed it. 14:04:14 From ted : Great job, Jim. Ted Hume 14:04:31 From Wayne R Pinnow : great meeting ... great effort to jim and bob 14:04:42 From Will Marchant : What an excellent conference! Thanks so much everyone for such a great event! 14:04:50 From Ace Hoffman : This has been wonderful! Thank you! 14:04:56 From Chris Hakkaart : Congratulations to organisers and presenters for this new style IM 14:04:56 From Gabriel Vanderdonck : Thank you all. Great meeting. 14:05:17 From jeff white : Thanks to all - great show! 14:05:34 From Murray Felstead (Ballarat, Australia [ VK3AAI ]) : Great meeting thanks 14:06:50 From Bob Adams (Adelaide Australia) to Jim Bready(Privately) : THanks Jim great meeting, anf I would like the link to dropbox for the slides 14:07:13 From Tom Frank (KA2CDK) : Thank you all very much for a wonderful gathering! I hope we can continue this approach, even as an adjunct to in person meetings in the future. (and no two hour drive home...) 14:07:43 From David Rance (NL) : Thanks especially to Bob and Jim but also to all who took part.. 14:08:32 From Andries de Man : Thanks for a very interesting, and really international, meeting! 14:09:55 From Curtis Jones : Bob, Jim, Thank you for doing a great job putting this together. Look forward to meeting again in person, but this is a better substitute than I expected. 14:12:18 From Simon van der Salm : Organizers: thank you very much for this wonderful IM. Thanks to all...it was a very interesting weekend