Wikipedia:Reference desk/Archives/Miscellaneous/2016 October 19

= October 19 =

Flying Alaska
On winter nights when visibility is bad (but not so bad as to be IFR), is it common for VFR traffic into Merrill Strip to land at Anchorage International Airport or Elmendorf AFB by mistake? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 01:17, 19 October 2016 (UTC)
 * Setting aside the question of what constitutes "common", it seems unlikely that such data is available. This article notes that
 * The Federal Aviation Administration investigates wrong airport landings and many near-landings, but those reports aren’t publicly available. FAA officials turned down a request by The Associated Press for access to those records, saying some may include information on possible violations of safety regulations by pilots and might be used in an enforcement action.
 * but goes on to note that commercial aviation in the US experiences about two wrong-airfield landings per year (35 discovered over a period of "over two decades"). The article also notes that the norm is for a larger airfield to be missed in favor of a smaller one; some of this is undoubtedly that commercial aviation tends not to operate out of GA airfields like Merrill in volume, but it may also be the case that pilots are less likely to confuse obviously-elaborate airfield layouts for expected small-field runway layouts. You can also search the NTSB database, filtered on Merrill (code MRI), Anchorage (ANC), etc.; a quick survey finds none for "incidents" (which is the category a non-fatal non-damaging wrong-airport landing would fall under, if investigated). I don't know whether that is the absence of such landings or a lack of formal investigation into them. &mdash; Lomn 19:35, 19 October 2016 (UTC)
 * So, no data one way or the other? 2601:646:8E01:7E0B:4DD7:6F54:E487:A4D9 (talk) 04:25, 20 October 2016 (UTC)

Cassini projection
I was looking through the article at List of map projections and came across a piece I don't understand. The second entry is the Cassini projection, which obviously looks a little wonky compared to most maps you see. Our description on the list says that "Transverse of equidistant projection; distances along central meridian are conserved. Distances perpendicular to central meridian are preserved." I guess my first question is: do preserve and conserve mean the same thing in this context - and, if not, where could I read up on the details? If they do mean the same thing, then I'm not sure I'm following. Looking at the map in either location, I agree that the distances along the meridian are conserved (in case I'm not using the term correctly, I mean that it appears that those distances are the same as what you get if you looked at a globe), but it doesn't look to me as if the same could be said of distances perpendicular to it. The Cassini projection shows the west coast of Central America getting closer to the prime meridian the further north you look, when that is the opposite of what you see on a globe. Or am I misunderstanding the term? The article on the projection uses slightly different language, saying that "Areas along the central meridian, and at right angles to it, are not distorted." The use of area here is particularly confusing to me as it would seem to imply that more than mere distances are being conserved (or preserved). Is there a good primer on this? Matt Deres (talk) 13:57, 19 October 2016 (UTC)


 * Note that the distance from a given point to the prime meridian is not along a circle of latitude (unless it's the equator). —Tamfang (talk) 21:22, 19 October 2016 (UTC)

Tap water
There have been ongoing controversies about how bottled water such as Aquafina or Dasani is just re-bottled tap water. Yet I feel like I can taste a difference between bottled water and whatever comes out of my tap at home - which to me, tastes chalky and disgusting. Are there documented differences between popular bottled water brands and municipal water in terms of taste and composition? Or is it just my imagination?--WaltCip (talk) 17:37, 19 October 2016 (UTC)
 * Here in the UK, "spring water" is a commercial term for "water" whilst "mineral water" is what most of us would be expecting.
 * There are many sources of commercial spring water which are supplied from the commercial water supply network, then bottled. Usually these are further purified, almost always by RO, and then re-mineralised to give a slightly "mineral water like" taste. Some restaurants even purify with their own RO units to provide table water under their own brand. RO water, in its purest form, has quite a distinct taste, partly due to its pH, partly due to its lack of the usual minerals we do expect. Commercial production for bottling though is likely to be sited somewhere where the water quality is already good (in the UK that would mean a soft water area to avoid any chalkiness) but aspects like a prominent chlorine taste can be dealt with by the purification. So yes, you may well find a taste difference just by drinking tap water from a few miles away, bottling is likely to be done from the best of these, and some tastes would have been removed.
 * Dasani was a failure in the UK, owing to the presence of some unexpected ingredients:, then from contamination by the production of bromates. Bromates aren't an issue in natural mineral water, but do arise from a reaction between natural bromides (harmless) and some of the purification or storage processes, such as UV microbial sterilisation or even just a sunny reservoir. Andy Dingley (talk) 18:10, 19 October 2016 (UTC)
 * This is an excellent answer. Thank you!--WaltCip (talk) 18:15, 19 October 2016 (UTC)
 * Interesting point about flavour due to pH. I'm assuming you're referring to the self-ionisation of water? That's only a tiny fraction of the water at any given time, is that going to contribute much to flavour? Or do you mean we're used to water at pH different than 7, due to dissolved minerals etc, and that's why neural water tastes different? Can't say I've noticed that much of a taste difference of RO/DI water myself. Fgf10 (talk) 21:57, 19 October 2016 (UTC)
 * I've drunk distilled water a couple of times, and it tastes flat (as near as I can describe it) -- so self-ionization does not contribute to the taste, and any taste other than flat is due to minerals and pH differences. 2601:646:8E01:7E0B:4DD7:6F54:E487:A4D9 (talk) 04:23, 20 October 2016 (UTC)
 * This is my experience as well, hence my question. Fgf10 (talk) 07:59, 20 October 2016 (UTC)
 * Here area few additional refs on taste and processing of bottled water that you may find useful  articles.mercola.com/sites/articles/archive/2011/01/21/best-and-worst-bottled-water-brands.aspx .   N.b., not all tap water is created equal. There are places I've lived where I'd have been happy to have a source of water bottled at the tap of my prior residence :) SemanticMantis (talk) 18:18, 19 October 2016 (UTC)
 * One of the things I have noticed is that in some cities the water coming from the tap tastes decidedly better than in neighboring cities, in some cases even better than the bottled water equivalent, though ultimately the water may originate from the same reservoir or water resource. I had in the past attributed it to poor piping.--WaltCip (talk) 18:20, 19 October 2016 (UTC)
 * In San Diego the tap water is particularly bad -- I think this could be due to brackish water contamination of the source, rather than the piping (if it was the piping, you'd expect it to taste rusty, but it tastes stale instead). Here in San Jose, though, the tap water is chalky but refreshing. 2601:646:8E01:7E0B:4DD7:6F54:E487:A4D9 (talk) 04:23, 20 October 2016 (UTC)


 * It depends on where the bottling plant is located, and what its water supply is. For example, there is a local Pepsi bottling plant located about 2 miles from my house, and it is supplied by the same municipal water supply as my own house is, so I wouldn't expect to taste much of a difference in said bottled water.  The difference between the taste of YOUR water supply at YOUR house and that of the bottled water sold in local shops can be explained if YOUR water supply is different from that of the bottling plant that supplies those stores.  If you want some additional reading on taste tests between tap and bottled water in general, I did find this article from 2011 (only 1 in 3 correctly identified tap water as different from bottled), here is another one with more results in a similar vein.  If you want to know why YOUR tap water tastes bad, This article provides a good synopsis.  -- Jayron 32 18:21, 19 October 2016 (UTC)


 * As a whiskey drinker, I think the 'disgusting taste' which the OP refers to is almost certainly down to chlorophenols and  not the piping. A single water utility company may be getting its water from many sources, such us underground aquifers, reservoir  and even sewerage plants. The more organic matter (that is too small to be filtered out), gets transform into phenols by the chlorine which is added. Human taste-buds can detect this down to  just a few parts in the million and thus leave the water  tasting tainted.  However, even with my delicate & refined taste-buds I don't have to resort to RO but find that an ordinary inexpensive domestic water purifiers incorporating activated charcoal and ion-exchange resins,  makes  the stuff coming out the tap acceptable to drink. The actual science ( pH, mineral content and all that stuff) is a little bit more complicated:>http://dwi.defra.gov.uk/research/completed-research/reports/dwi0030.pdf&sa=U&ved=0ahUKEwid-8y83-fPAhWMJsAKHQl_A0MQFggbMAA&usg=AFQjCNGrE--LiTk8yfzbDEZb9KC3rwIZXg< but I think it is worth trying out a cheap purifier first. Bottling plants also treat their water to provide a standard product regardless of where it is bottled, which normally includes  passing it through zeolite filters etc.--Aspro (talk) 21:58, 19 October 2016 (UTC)


 * One item that I don't think has been touched yet is the presence of air in the water. The water from your tap will have a lot of dissolved air in it (even if you're not intentionally adding it) which will affect both temperature and taste. On the other hand, stowing the water in the fridge may also introduce unwanted flavours as the water picks up the scents of your leftover pickles and olives. Matt Deres (talk) 16:33, 20 October 2016 (UTC)


 * My sisters and I grew up getting our tap water from the Kirkwood-Cohansey aquifer at the edge of the South Jersey Pine Barrens, which is noted for its purity. I don't consider it "flat" but I won't drink it without at least ice to give it some character.  When we visited my grandparents in South Philly, however, the first thing we would do after greeting them was to crack the icetray and get some ice, which tasted mildly of sulfur.  This was even before we'd ask for M&M's or Milkbone Dog Biscuits.  I was surprised when I moved to NYC to learn that the water tasted no different from that of the Kirkwood-Cohansey aquifer. μηδείς (talk) 00:40, 21 October 2016 (UTC)


 * FYI, New York City consistently has some of the best rated tap water in the U.S. See New York City water supply system, i.e. here where it is named one of the top 10 municipal water systems in the U.S.  -- Jayron 32 03:08, 21 October 2016 (UTC)
 * Thanks, Jayron32, yes; that was sort of my point. Given I was born in NY and lived there since I was 23 it didn't seem appropriate to brag about the quality of NYC water, but it is very good. μηδείς (talk) 04:18, 22 October 2016 (UTC)


 * To add an example of how different tap waters can be, consider the Flint water crisis, where they switched from the excellent Detroit water (relatively unpolluted Lake Huron water, etc., that is properly treated) to polluted and improperly treated Flint River water. The difference was not only in taste, but in many measurable ways.


 * Also, note that letting tap water sit in the refrigerator (in a sealed container), allows the chlorine taste to dissipate. StuRat (talk) 17:15, 22 October 2016 (UTC)
 * Do please provide a reference for this. That's a fascinating factoid.--WaltCip (talk) 12:06, 24 October 2016 (UTC)


 * Here's a source that discusses this method for making tap water safe for aquariums: . StuRat (talk) 14:08, 24 October 2016 (UTC)


 * Far as I can tell, that source is only talking about using unsealed containers. Nil Einne (talk) 04:41, 25 October 2016 (UTC)


 * The idea of the sealed container is so it won't pick up microbes from the air once it loses it's chlorine protection. Do you suspect sealing the container will stop the outgassing of chlorine ? StuRat (talk) 05:30, 28 October 2016 (UTC)


 * Also note that some bottled water brands purify their water and then intentionally add minerals to it so that it doesn't taste flat. The bottle will usually tell you. shoy (reactions) 13:26, 25 October 2016 (UTC)

"Electrical ant"
Does everyone know, how this Yale Electric Industrial Truck was steered? By the foot pedals?--Kopiersperre (talk) 22:20, 19 October 2016 (UTC)


 * I have a dim memory of similar trolleys being used at London rail termini in the 1960s. I found this picture of one in use, the driver stands facing forward with his back to the truck and steers with the projecting arm (the one in my picture has two arms - not at all sure how that works). I suspect that the operator had to be standing on both pedals to make it go. All this is a bit conjectural, so I'm hoping someone else knows better. Alansplodge (talk) 00:13, 20 October 2016 (UTC)
 * I've googled every search term I can think of and only found a toy one. Alansplodge (talk) 00:29, 20 October 2016 (UTC)
 * Success! Here's a rather jolly lady driving one in the First World War. No pedals though or maybe one big one. But perhaps yours is completely different, who knows? Alansplodge (talk) 00:32, 20 October 2016 (UTC)
 * A steering device like that is usually called a tiller. -- Jayron 32 01:08, 20 October 2016 (UTC)
 * Of course! I knew there was a word for it - thanks. Alansplodge (talk) 08:19, 20 October 2016 (UTC)