Re: Water Bucket
Hi All, I think David has it right. When I put a hose into my swimming pool (a very large bucket) the effect is barely noticable - probably caused only by local eddies. When it is put into a small bucket with the same nozzle it becomes pronounced. With no nozzle the effect is *greatly* diminished in the bucket (but it is still there). I'll have to try it with a hose with the end cleanly cut off - a hose with no bluff. I think I have some in the garage somewhere... I might have a few different sized buckets to try too... The temperature will be in the mid to high 90's (35+ c) here today. This will be a good excuse to stop working for a while and go for a swim! On Sundials - A while back on the cover of Science News Magazine there was a sundial in the shape of a boat in a pond. The sail of the boat provided the style/gnomon. When water was in the pond the shadow was refracted to a different hour line than when the pond was dry. I don't remember what this 'correction' was used for. Has anyone used refraction of light in in water for casting shadows in this way? Chuck O'Connell Massachusetts, USA Message text written by David Higgon For simplicity, consider the hose vertical and aligned to the centre of the bucket. This will set up a flow that goes down the middle of the bucket, radial out when it gets to the bottom, up the sides and radially back in to the middle at the top (roughly speaking). When the hose is inserted into the middle, it is basically being put into a liquid that is flowing vertically down - what is happening in the rest of the bucket I believe is relatively incidental.
Re: Water Bucket
Message text written by Tony Moss BUT as soon as the veriest tip of the nozzle touches the surface of the water it is 'snatched' downwards. I wonder if there is a surface tension/capillary type effect happening here (probably not)... -- or perhaps the effect is most pronounced near the surface where the kinetic energy of the water isn't dissipated by the water/air interface as effectively as when the jet is totally submerged and surrounded by 'lots' of water which may be able to transfer the energy away rather than causing turbulance. One other point - As Tony (re: the scoop paddles) and David (re: bluffs) noted: the geometry of the nozzle itself may have a profound impact on the effect. I'll bet the flow rate has a huge impact too. I'll try it with other nozzles to see what happens Chuck
Re: Water Bucket
Hi, How about this - The jet rushing in to the water creates a 'hole'. This hole is caused by the fact that water is pushed down and away in the direction of the jet. is flowing. The water in the bucket rushes in to fill the hole - a vacuum has been created by the fact that water is being pushed away. When the nozzle is available to plug the hole and respond to the vacuum it is pulled in. Why does this effect not continue for the entire depth of the bucket? I think this is because the pressure difference is greatest at the air/water interface. Once in the water the energy that creates the hole is expended pulling 'bucket' water in. The flowable bucket water will respond *much* more readily to the vacuum than the 'non-flowing' (solid) hose. I think that is it. A simple vacuum created by pushing water out of the way and by imparting some kinetic energy to it. Chuck. (The elephant is very much like a rope! said the blind man holding it's tail...)
RE: My new site WEB
Message text written by Angelo Brazzi I'm pleased to announce that my Web site is opened at the address: http://web.tiscalinet.it/partena/index.htm Angelo - You are both a skilled diallist and a skilled artist! You have some very nice works - not at all rough - in fact they are very nice! Chuck
Gryphon Sundial.
Message text written by Luke Coletti I just acquired a Gryphon dial Good for You! I have no information to offer, but *I AM JEALOUS!* How did you happen to find it? Chuck
Re: Metal expansion with heat- Sodium.
Message text written by INTERNET:[EMAIL PROTECTED] PS: sodium would be really fun with a garden dial! Yeah ,especially when it rains. The sundial that makes it's own light during rainstorms Gee - maybe magnesium would be good too! Message text written by Tony Moss Please ignore the load of rubbish I recently sent about linear expansion of metals. Don't be so hard on yourself Tony, after all, whats a few decimal points among friends! I had to think there was a missing 10^x in there somewhere after trying the numbers. Thanks for the clear explaination of how to apply the numbers. Chuck
Metal expansion with heat.
Hi All, I've a question related to the casting of metal sundials. Which metals expand the most with heating and by how much? (I don't want the best behaved - I want the *worst* - metals that expand the *most*). If I remember rightly, Tony Moss made reference to metal expansion in an earlier e-mail. Thanks, Chuck.
RE: portable Boy Scout sundial - SUNWATCH
Message text written by John Carmichael It is impossible to read the name of the manufacturer that is printed on the face below the compass in the photograph. Hi John, I can just about read it in my version: Outdoor Supply Co. Inc The state could be NY, USA or KY, USA or NV USA Hope this helps! Chuck
A Laugh
Hi All, In dredging the internet for sundial related stuff I came across an activity for parents to do with kids. It was to build a sundial - which is good! The last instruction given was: 'Make sure to take the sundial outside on a sunny day for maximum effect. ' Chuck
RE a better eclipse filter - an anecdote.
Message text written by John Carmichael By the way, did you know that you can use a shadow sharpener to see sunspots on the sun? Hi John, It's hard to see if the image is too small though. The most unusual way I've ever seen sunspots is *directly*. I was driving west at sunset on an *extremely humid* hot august evening. As my car crested a hill the sun was sitting on the horizon, *easily* viewable because it was so washed out by the haze. I could not believe my eyes - I could clearly make out 2 large sunspots and 3 smaller ones. I think the sunspots were probably monstrous as far as sunspots go I've never seen them with the naked eye again although I try to look when the conditions are comparable. Chuck
RE; Endangered Sundials
Hi All, We've been discussing sundial 'safety' in regards to publishing photos on the web. I still believe it is a good project. The following URL shows a prime example of the stupid nonsense that goes on out there. For me it is a real eye-opener. Please visit this URL: http://members.aol.com/rusty39538/sundial.html Not even shear size protects some works. Chuck.
A Memorial Sundial
Hi All, I won't bother you with any more URL's for a while, but I found this one and it really touched me. You may already know about it, but I didn't. Kentucky is a state in the USA. These people were lost in the vietnam war. The following text is part of a web-page about it: 'There are 1,100 names of Kentuckians on the memorial, including 23 missing in action. Each name is engraved into the plaza, and placed so that the tip of the shadow touches his name on the anniversary of his death, thus giving each fallen veteran a personal Memorial Day. ' URL: http://www.helmr.com/ky.htm Chuck
Should we have a web site for sundial photos?
Message text written by INTERNET:[EMAIL PROTECTED] I understand if we divulge sundials addresses and attractiveness on the Intenert (or any other means), we may get the attention of some ill-intentioned person. True - but we don't have to publish the ADDRESSES!! Fernando, I agree with you - if they can't be seen, they might as well have been stolen already! We should perhaps have a 'debate' about this, I think a web site could be safely managed without jeopardizing our beloved sundials. I would like to create such a site, but I would not want to do it if people feel strongly that it would endanger the dials. We are all entitled to our opinions, and I'm the first to admit that I'm not always correct - If there were enough doubt I would not do it. Your thoughts, please? Chuck.
Albert Waugh
Hi All, Does anybody know if Albert Waugh still living? If so, where might he be found? 25 years ago I bought my first copy of his book 'Sundials - Their theory and construction'. I've been a sundial fanatic ever since. Chuck
Is there a single web site for sundial photos?
François wrote: I took a picture and scanned it for who would like to see it: http://web.fc-net.fr/frb/sundials/photos/chicago.jpg The sundial is located on a kind of peninsula where there's a wonderful sight on Chicago down-town. Thanks for the advice. Thanks for posting the picture on your web site - It's beautiful! Question for all - Is there any one place where sundial photos are achived, indexed and accessible on the web? If not there should be! Perhaps with some significant and standard data about each one, and perhaps thumbnails too... This sounds like a worthy project.
RE: Is there a single web site for sundial photos?
Patrick and All, I didn't realize there was a great deal of theft of sundials. That is really sad, pathetic. Here in the US we don't have the plethora of ancient sundials that you do. I don't know of many old specimens around here that are worth stealing! A lot of what we do have are 'industrial scale' dials, if you take my meaning. It would be possible to have a central site that enumerates and displays images of the dials without giving their location any closer than county or town. There is a lot of information that could be given - date, manufacturer, furniture, what it is made of, errors, you get the idea. Yes - these things must be protected, but they should not be buried! Chuck
RE: Albert Waugh
Message text written by Frederick W. Sawyer III Albert Waugh died in 1985 at the age of 82 Fred, Thanks for the info. It always seems that the people I would like to meet have passed away before I realize that I want to meet them. I live only an hour away from connecticut where he lived. Chuck.
Re: a peculiar sharpener
Message text written by Jim Cobb I remember many years ago during a partial eclipse looking at the shade under a young tree. On the ground was a profusion of pinhole images of the eclipsed sun, formed by the random gaps between the leaves. Subsequently I've read of this effect in astronomy magazines. It's worth looking for, if you get the chance. I have seen this too - it was almost surrealistic! Chuck
RE: a peculiar sharpener
Hello All, The discussion about 'shadow sharpeners' is interesting. When diffraction was mentioned I wondered if a 'double-slit' diffraction apparatus and the resulting interference pattern could be used as (or with) a vernier scale to further increase resolution... I'll have to play with this! Chuck
precisely accurate
Message text written by Phil Pappas Hello Old Timers: Who are you calling an 'Old-Timer'? To be precisely accurate, I don't think I'm old at 42!! To be accurately precise I don't think it much matters if you use precise or accurate. The public will know what you mean. Chuck (An Old-Timer wannabe!)
RE: Unusual sundial.
Hi Everyone, Thanks to all for the flood of info about the Campbell-Stokes recorder. About the sundial Fernando took photos of: I came across this sundial and wonder if it is our mystery sundials cousin. See this page: http://www.wengersundial.com/Picture.UniGlobe.html Food for thought. Chuck.
Name of sunlight recording device.
Hi Everyone, Does anybody know the name the device described below? It looks like a glass sphere held in the center of a small equatorial sundial. The image of the sun focuses to a point at some short distance away from the surface of the glass sphere. Held in place at this distance away from the glass and following the curve of the sphere is a piece of waxpaper against a dark background. When the sun shines, the waxpaper is scorched. When the sun is behind the clouds, it is not scorched. The result is a recording of the amount of sunshine seen at that location on that day. At least this is how it appears to me from a picture I have seen. Anybody have a name and possibly a source to buy one? Thanks, Chuck.
Re: dial furniture
Message text written by fer j. de vries I agree with your remark 'dial furniture can so easily be overdone'. I more like to make a number of dials with less furniture than to put to many in one dial. I usually prefer to make mine 'clean' also - but sometimes 'baroque' is nice too! Chuck.
RE: Dallas airport dial - Not just Dallas!!!!
Hi All, John Carmichael wrote: The sundial I saw out my window while landing in Dallas was DEFINITELY a large horizontal dial with hour markers and a bright red gnomon pointing north at about the right angle. It was not navigation equipment! It was cloudy that day so I couldn't tell the time. It seems there may be more than 1of them! I've recently (last year or so) seen a dial at an airport. I don't remember if it was in Atlanta, Georgia, Orlando, Florida, or Geneva, Switzerland. I'm a pilot and I can assure you it was a sundial and not a VOR or VORTAC - ( which could easily look like a sundial, especially when it has an orange or red wind sock being filled by a slight breeze ). I remember when I spotted the dial I thought - geez, that's an odd looking VOR - so I looked closer. It was a sundial! I wish I could remember for sure where I saw it. It was before I joined this list. Chuck O'Connell
Sundial furniture list
Hello All, Does anybody know of a 'fairly complete' list of things people put on their sundials? (sundial furniture) By this I mean hour lines, date lines, unusual uses, etc. There is a solar refraction phenomenon called 'circum zenithal arcs' which occur only when the sun is between 18 and 26 (or is it 16-28) degrees in the sky. It appears as a blue shifted rainbow that appears directly overhead as a circle centered at the zenith! I'm including lines on my sundial to show when the sun is between these altitudes. It got me wondering what else people have put on theirs. Chuck
RE: Circumzenithal Arcs and Furniture.
Message text written by INTERNET:[EMAIL PROTECTED] RE Circumzenithal Arc This sounds interesting... the sun is in that range here as we speak. Could you fill me in on what I'm looking for, and the conditions (time of day, weather, etc) necessary? I've attached a JPG that pretty well shows the sky conditions. It is only of a partial arc, but it gets the idea across. The time of day? Well, when the sun has an altitude of between 18-26 degrees above the horizon. The time depends on the time of sunrise and sunset. I start looking from 3 hours after untll 4 hrs and 20 minutes after sunrise. I look again from 4:20 before sunset until 3 Hrs before sunset. (I think my math is correct, but...) I use : Solar Hour Angle = 18 degrees /sin(23.5)(45.14 degrees HA - 3 hours) and : Solar Hour Angle = 26 degrees /sin(23.5)(65.2 degrees HA - 4:20 ) I'm including lines on my sundial to show when the sun is between these altitudes. Please forgive me for attaching the JPG, but I didn't think it was too big. I got it from The Audubon Society Field Guide to North American Weather. They have a good amount of info on solar refraction/reflection phenomenon. It's a great book if you have any interest in the weather and clouds. The pictures are fantastic! Chuck. Attachment converted: MAC Hard Disk:zenarc.jpg (JPEG/JVWR) (F820)
RE: Circumzenithal Arcs and Furniture - OOPS!!!
Hi, I goofed. Message text written by Chuck O'Connell (I think my math is correct, but...) I use : Solar Hour Angle = 18 degrees /sin(23.5)(45.14 degrees HA - 3 hours) and : Solar Hour Angle = 26 degrees /sin(23.5)(65.2 degrees HA - 4:20 ) The above formulae are clearly wrong. I don't know what I was thinking. Try this instead: HA = 18/sin(90 - yourLatitude + solarDeclination) HA = 26/sin(90 - yourLatitude + solarDeclination) Please let me know if this is correct. I hate foolish mistakes. The first gives the hour angle from sunrise (or sunset) when the sun is 18 degrees above the horizon. The second is the hour angle for 26 degrees. When Sol is between these you may see a circumzenithal arc if there are high thin ice clouds. Chuck.
Slate Sundials: Looking for advice...
Hi Everyone, A while back some people mentioned some drill bits, burrs and handtools they used to carve stone sundials. I can't find the e-mails. Would you be so kind as to repeat what was written - or provide new info? Thanks, Chuck [EMAIL PROTECTED]
RE: Window pane refraction, polarization and Sellotape
Hello All, Tony wrote: I can't speak for other areas but hereabouts the interglazing space in double glazing is filled with argon, not air, from which it has a different 'refractive index' - I think my physics teacher might have said if I'd had one. (WW2 - no teachers - just nuns!) Does the maintained parallelism of an air/glass/air/glass/air interface still apply? Yep! It sure does! Chuck [EMAIL PROTECTED] PS: Patrick - Thanks for the pointer to Sellotape. I'll check it out. Edward - Thanks for the pointer to Edmunds Scientific. I had forgotten about them.
