sbeme wrote:
Is a helix a spiral with an added dimension?
No! A spiral has a decreasing radius, a helix has a constant radius (like all those helical notebooks you bought for school... you DID call the helical right?)
None of which detracts from the picture of course. I still like it and think it's worthy of inclusion despite the misnomer.
TrojanHorse wrote:
No! A spiral has a decreasing radius, a helix has a constant radius (like all those helical notebooks you bought for school... you DID call the helical right?)
None of which detracts from the picture of course. I still like it and think it's worthy of inclusion despite the misnomer.
In fact, one could go further and call this a double helix.
Wordinfo defines speira (Greek) spira (Latin) saying "The Greek speira refers to anything which is wound or wrapped around something" which sounds like it covers helices and spirals...
There are at least two instances in which "spiral" is used as a synonym for "helix". A "spiral stair case" and a "spiral bound" book.
I like this one a lot Carolyn, but I also liked your original post, regardless of nitpicking the geometry. I've always heard them referred to as "spiral" staircases. Ah, got to the love the UN-moderated forums!
I much prefer this image. It's certainly my favourite shell shot out of all the entries. I love the composition, contrast of black and white and the reflection is superb. Good luck!
) calls them helical staircases or helical-bound notebooks etc. 
The new one is lovely. It has a sense of "cleanness" in it. Great shot, as always.