zawada@en.ecn.purdue.edu (Paul J Zawada) (06/25/90)
unhd!unhtel!paul@uunet.uu.net (Paul S. Sawyer): > In article <9096@accuvax.nwu.edu> 0004133373@mcimail.com (Donald E. > Kimberlin) writes: >>I have walked in the streets of Paterson, NJ and seen manhole covers >>marked, "New York Bell." this, of course, is plant long since taken >>over by NJ Bell, but it is the physical remnants of that history and >>time when NYTel ran the phones in northern NJ. >>Perhaps some of our more intrepid readers would engage some vicarious >>manhole-cover-reading. Might be of trivial interest. How about it? > Throughout our campus, the manhole covers have the Bell logo and say > "Bell System", although we own them and the cables/conduits below.... > They were installed in 1985 by the people who USED to be the Bell > System - we figure they were just leftovers. Back in the early 70's, when Illinois Bell provided service to Northwest Indiana (Gary, Hammond, East Chicago), they deployed a number of manhole covers with the Bell System logo and the initials I.B.T. This, of course did not leave any historical reminders when Indiana Bell took over the service area in the mid-seventies. Has anyone ever seen a "recycled" Bell System manhole cover? I've seen a few of these in West Lafayette, IN, which is served by GTE North. (The rest of the manhole covers have the GTE logo on them.) The "recycled" covers have no noticeable logo, but upon closer inspection one can see a faint Bell System logo and the name "Bell System". It looks like the name and logo were ground off somehow. Paul J Zawada | zawada@ee.ecn.purdue.edu Titan P3 Workstation Support | ...!pur-ee!zawada Purdue University | Engineering Computer Network
yarvin-norman@cs.yale.edu (Norman Yarvin) (06/26/90)
rees@dabo.ifs.umich.edu (Jim Rees) writes: >>Has anyone ever noticed non-round manhole covers? Nashua and Hudson, >>N.H. have TRIANGULAR ones - don't know what service or utility. >I think this has been discussed before. Round covers are popular >because it's impossible for the cover to fall into the hole. This also holds for triangular covers. (only if they are equilateral, though.) Norman Yarvin yarvin-norman@cs.yale.edu
rpw3%rigden.wpd@sgi.com (Rob Warnock) (06/26/90)
In article <9180@accuvax.nwu.edu> unhd!unhtel!paul@uunet.uu.net (Paul S. Sawyer) writes: | By the way, what about a non-sexist term like "utility access cover"? | ("person hole" just doesn't make it.... B-) The city of Sacramento, California, has recently decided to call them "maintenance holes", which -- besides being decently neuter and even descriptive -- means they won't have to change the hundreds of City bluprints which have them marked as "M-H"! Rob Warnock, MS-9U/510 rpw3@sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311
leichter@lrw.com (Jerry Leichter) (06/26/90)
Norman Yarvin claims that a triangular manhole cover cannot fall through its own hole "if it's equilateral". As Spock said in Star Trek: The Wrath of Kahn - he displays two-dimensional thinking. Stand an equilateral triangle up on one corner so that one side is perpendicular to the ground. Its maximum cross-section is now the height of the triangle, which is quite a bit less than the length of one side. (sqrt(3)/2 times as large, about .866). It can thus easily be dropped through its own hole by keeping it resting along one edge of the hole. There ARE geometrical figures other than circles whose cross-section is constant at all points - Scientific American's Mathematical Games section had articles on this years ago, with speculations about carriages with wheels of this shape. The simplest such figure is easy to draw: Start with an equilateral triangle. From each corner, draw a circular arc joining the other two corners. The resulting "bulging" triangle has the required property. As a result, it cannot fall into its own hole if used as a manhole cover. As I recall, such covers are actually used somewhere! BTW, someone brought up the issue of "non-sexist" names for manhole covers. There was an article in the paper about this a couple of days ago. It seems that some city - San Diego? - has adopted new language for the things on all official city maps and drawings - something like "service access portal". The change started out as a joke which someone took seriously. -- Jerry P A T R I C K A. T O W N S O N (The Cheerful Iconclast) ptownson@cs.bu.edu ptownson@chinet.ch.il.us ptownson@eecs.nwu.edu Unique Zip Code 60690-1570 MCI Mail: 222-4956 AT&T Mail: !ptownson
malloy@nprdc.navy.mil (Sean Malloy) (06/27/90)
In article <9206@accuvax.nwu.edu> rees@dabo.ifs.umich.edu (Jim Rees) writes: >>Has anyone ever noticed non-round manhole covers? Nashua and Hudson, >>N.H. have TRIANGULAR ones - don't know what service or utility. >I think this has been discussed before. Round covers are popular >because it's impossible for the cover to fall into the hole. You're missing the other reason -- manhole covers are round because it reduces the complexity of the decision the workers have to make when putting it back. Sean Malloy Navy Personnel Research & Development Center San Diego, CA 92152-6800 malloy@nprdc.navy.mil P A T R I C K A. T O W N S O N (The Cheerful Iconclast) ptownson@cs.bu.edu ptownson@chinet.ch.il.us ptownson@eecs.nwu.edu Unique Zip Code 60690-1570 MCI Mail: 222-4956 AT&T Mail: !ptownson
cdc@uafhp.uark.edu (C. D. Covington) (06/27/90)
In article <9276@accuvax.nwu.edu>, yarvin-norman@cs.yale.edu (Norman Yarvin) writes: > rees@dabo.ifs.umich.edu (Jim Rees) writes: > >>Has anyone ever noticed non-round manhole covers? Nashua and Hudson, > >>N.H. have TRIANGULAR ones - don't know what service or utility. > >I think this has been discussed before. Round covers are popular > >because it's impossible for the cover to fall into the hole. > This also holds for triangular covers. (only if they are equilateral, > though.) I can't keep from jumping in on this last comment. I don't believe this to be true. The property of round covers that keeps them from falling through is that of constant width. There exist an entire family of possible closed curves of constant width, the most obvious being a perfect circle. An equilateral triangle is not one of them. On the other hand, if you take the vertices of the equilateral triangle and use a compass to construct three arcs, each passing through two vertices and using the other vertex as a center point, then an alternative curve of constant width results. That is, if the points A, B, and C are equidistant from each other. The place the compass point on A and draw an arc from B to C, and repeat this process with the point on B and then C, drawing arcs to the remaining points. A manhole cover constructed in this way will not fall through. Try it by cutting this shape out of a piece of cardboard and dropping it against the hole you made cutting it out. It works! C. David Covington (WA5TGF) cdc@uafhcx.uark.edu (501) 575-6583 Asst Prof, Elec Eng Univ of Arkansas Fayetteville, AR 72701 P A T R I C K A. T O W N S O N (The Cheerful Iconclast) ptownson@cs.bu.edu ptownson@chinet.ch.il.us ptownson@eecs.nwu.edu Unique Zip Code 60690-1570 MCI Mail: 222-4956 AT&T Mail: !ptownson
msb@sq.com (Mark Brader) (06/28/90)
>>I think this has been discussed before. Round covers are popular >>because it's impossible for the cover to fall into the hole. >This also holds for triangular covers. (only if they are equilateral, >though.) Hold the lid with one edge vertical, and it will go in just fine if placed next to one edge of the opening. So an equilateral triangle *doesn't* work. What does work is a "Reuleaux triangle", where each side is not a straight line but an arc centered on the opposite vertex. This is the second-simplest (after the circle) of what are called "curves of constant breadth", any of which will also work. However, round covers have the additional advantage that there is no wrong way to put them in the hole. Mark Brader SoftQuad Inc., Toronto utzoo!sq!msb, msb@sq.com P A T R I C K A. T O W N S O N (The Cheerful Iconclast) ptownson@cs.bu.edu ptownson@chinet.ch.il.us ptownson@eecs.nwu.edu Unique Zip Code 60690-1570 MCI Mail: 222-4956 AT&T Mail: !ptownson
kaufman@Neon.Stanford.EDU (Marc T. Kaufman) (07/01/90)
In article <59794@bu.edu.bu.edu> msb@sq.com (Mark Brader) writes: >Hold the lid with one edge vertical, and it will go in just fine if >placed next to one edge of the opening. So an equilateral triangle >*doesn't* work. Uh ... on that basis, a circle doesn't either. The diameter will allow a circle of the same diameter to pass edge on. On the other hand, most REAL *hole covers I have seen are set into a flanged ring that has a smaller diameter than the maximum diameter of the cover. Presumably this is to insure that the covers stay flush with the street, and don't fall to the bottom of the hole. I imagine that triangular covers are installed similarly. Based on this discussion, I think I am glad that computer scientists or telephone engineers did not design these things. Marc Kaufman (kaufman@Neon.stanford.edu)
clive@ixi-limited.co.uk (Clive Feather) (07/06/90)
People have been talking about constant width curves (such as a triangle with curved sides, each centred on the opposite vertex). The UK 20p and 50p coins are seven-sided constant width curves in shape. The constant width property means that the coin will still roll ! Clive D.W. Feather | IXI Limited clive@x.co.uk [x, not ixi] | 62-74 Burleigh St. ...!uunet!ixi!clive | Cambridge CB1 1OJ Phone: +44 223 462 131 | United Kingdom
"John V. Zambito" <jvz@cci632.uucp> (07/11/90)
>>>I think this has been discussed before. Round covers are popular >>>because it's impossible for the cover to fall into the hole. >However, round covers have the additional advantage that there is no >wrong way to put them in the hole. This discussion got way out of hand, but let me add to it. What about when a stripe from a lane marking is painted on it? The service people never put the cover back on right. [Moderator's Note: I see lots of these in Chicago. Typically, they are always turned at some strange angle to the rest of the line. PT] ..
nam2254%dsacg2.dsac.dla.mil@dsac.dla.mil (Tom Ohmer) (07/12/90)
From article <9578@accuvax.nwu.edu>, by jvz@cci632.uucp (John V.
Zambito):
< This discussion got way out of hand, but let me add to it. What about
< when a stripe from a lane marking is painted on it? The service people
< never put the cover back on right.
< [Moderator's Note: I see lots of these in Chicago. Typically, they are
< always turned at some strange angle to the rest of the line. PT]
Unless they are held in place, and ones I've examined are not, being
driven over would cause them to rotate, albiet slowly, no?
Tom Ohmer @ Defense Logistics Agency Systems Automation Center,
DSAC-AMB, Bldg. 27-6, P.O. Box 1605, Columbus, OH 43216-5002
UUCP: ...osu-cis!dsac!tohmer INTERNET: tohmer@dsac.dla.mil
Phone: (614) 238-9210 AutoVoN: 850-9210 Disclaimer claimedsegal@uunet.uu.net (Gary Segal) (07/13/90)
jvz@cci632.uucp (John V. Zambito) writes: >This discussion got way out of hand, but let me add to it. What about >when a stripe from a lane marking is painted on it? The service people >never put the cover back on right. >[Moderator's Note: I see lots of these in Chicago. Typically, they are >always turned at some strange angle to the rest of the line. PT] The solution is so simple, I can't imagine why the streets department hasn't figured it out yet: Paint the entire manhole cover yellow, that way no matter how the cover is rotated when it's put back, the line will always go across!!! :-) Gary Segal ...!uunet!motcid!segal +1-708-632-2354 Motorola INC., 1501 W. Shure Drive, Arlington Heights IL, 60004 The opinions expressed above are those of the author, and do not consititue the opinions of Motorola INC.