When you use a ruler or scale, you can be biased towards seeing the numbers you want to see.
I used a pair of micrometers and measured 5 discs and consistently got a reading between 89.9 and 90.1 mm. The other dimension reads between 93.5 and 94.5 mm. If I use a ruler, I can get anywhere between 89 and 90 depending on where I put the zero line. Try using a set of micrometers to eliminate your bias is trying to "prove" the discs are not 90 mm. Euric ----- Original Message ----- From: "Gavin Young" <[EMAIL PROTECTED]> To: "BigChimp" <[EMAIL PROTECTED]> Cc: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Wednesday, 2004-04-07 02:47 Subject: Re: [USMA:29441] Re: USMA digest 1568 - floppies really are 3.5 in. on one side > Most all of my 3.5" inch disks have the dimmensions I indicated, namely 89 mm x > 93 mm, including my orginal Microsoft and Apple Computer operating system > software disks. Those software disks have copyright dates of 1990 to 1997. > Today I noticed that some of the disks measure 89.5 mm by 93 mm, but none > appear to be as big as 90 mm x 94 mm. > > 89 mm = 35.03937 inches and that appears to be the size of most of my disks. > Have you measured your disks, if so what size are they? > > When was this ISO standard made and is it binding? Afterall there is an ISO > date and 24 hour time standard, but most businesses in the USA are not > exclusively using it (if they are using it at all). > > Quoting BigChimp <[EMAIL PROTECTED]>: > > > > > There is no such thing as a 3.5 inch floppy disc. > > The term 3.5 inch floppy disc is in fact a misnomer. Whilst the specification > > for 5.25 inch floppy discs employs Imperial units, the later specification > > for the smaller floppy discs employs metric units. > > > > The standards for these discs are ISO/IEC 8860-1:1987 (double density), > > ISO/IEC 9529-1:1989 (high density) and ISO 10994-1:1992 (extra-high density); > > all of which specify the measurements in metric. These standards explicitly > > give the dimensions as 90.0mm by 94.0mm. > > > > In most countries, the national standard is simply derived from the ISO > > standard. In the U.S., however, the applicable standard is instead ANSI > > X3.171-1989. That, too, specifies the measurements in metric, though. It > > specifies the catridge dimensions as 90.0mm by 94.0mm by 3.3mm and the > > diameter of the magnetic disc material itself as 85.80mm. > > > > If you have a floppy disc catridge that does not measure 90mm, then you have > > one manufactured by someone that is not careful about manufacturing > > tolerances. (And you should beware. If their product isn't up to > > specification in one area, it may not be so in others.) If the disc measures > > 3.5 inches, then it is the wrong size. 90.0mm is 3.5433 inches. > > > > > > -------------------------------------------------------------------------- ---- > -- > > > > � Copyright 2003-2003 Jonathan de Boyne Pollard. All rights reserved. "Moral" > > rights asserted. > > Permission is hereby granted to copy and to distribute this web page in its > > original, unmodified form as long as datestamp information is preserved. > > > > From: > > http://homepages.tesco.net/~J.deBoynePollard/FGA/floppy-discs-are-90mm-not-3- > and-a-half-inches.html > > > > > > How did you measure the disks? Did you use a ruler or a set of micrometers? > > > > > > If you insist your disks are really not dimensioned to the ISO/IEC standard, > > then refer to the 4-th paragraph above. > > > > Euric > > > > > > > > > > > > > > ----- Original Message ----- > > From: "Gavin Young" <[EMAIL PROTECTED]> > > To: "U.S. Metric Association" <[EMAIL PROTECTED]> > > Sent: Monday, 2004-04-05 14:28 > > Subject: [USMA:29441] Re: USMA digest 1568 - floppies really are 3.5 in. on > > one side > > > > > > > I don't understand why people say that a 3.5 inch floppy is not really 3.5 > > > > > inches. When I measure my floppy disks to the nearest 1/32 of an inch, the > > > > > dimentions are 3 1/2 in. by 3 5/8 inches. Thus one side is truly 3.5 > > inches. > > > Some prometric websites say that instead of 3.5 inches it is really 90 mm, > > > > > however my disks measure 89 mm x 93 mm. It is the opening to the floppy > > drive > > > bay that is 90 mm wide (the disk has to be slightly smaller or else it > > won't > > > slide into the drive)! Prometric people need to get the facts straight if > > they > > > are to be credible to nonmetric people. > > > > > > Likewise the diagonal measure of computer monitors and TV screens are still > > > > > stated exclusively in inches in the USA, even though the dot pitch is > > stated in > > > mm. Since the dot metric is stated in metric, I wonder why the diagonal > > measure > > > is not also stated in metric. I guess it is because people don't pay much > > > attention to the dot pitch except when comparing specs, but the diagonal > > > meausure is something they visualize when they see advertising. > > > > > > Trade Name! > > > > > > It's just a trade name. Just like a half-inch pipe is not really a half > > > inch nor is a 3.5 inch floppy really 3.5 inches. > > > > > > I have an idea. Why don't you take the pot back to the shop you bought it > > > from or call them on the phone, explain what you did and ask them how a 2 > > L > > > pot can be called a gallon pot! Then report here. I'd be surprised to > > read > > > clerk's answer. > > > > > > BTW. when you measured it as 2.25 L, were you filling it to the rim with > > > something? If you were, that is wrong. Flower pots are never filled > > full. > > > There has to be some space for debris and watering. That may in fact be > > > meant to be a 2 L pot. > > > > > > > > > Gavin Young > http://www.xprt.net/~hightech , http://www.renewableelectricity.com, > http://www.electric-automobile.com >
