Putter Length vs Weight

[Tom54]

I currently game a 32" putter that weighs approximately 360g. The other weekend I went to a putter demo at my course with one of the teaching pros. He recommended me going to a 35" putter to get me standing more upright and less hunched over as I am now. In the name of future back preservation, I'm thinking of it.

 

Here's my question: Why does the weight of the putter generally go down as the putter gets longer? For example, if you look at the Standard column on the Scotty Cameron site, there's less extra weight at 35" than at 33". So while a 33" offering would be 360g, the 35" is 340g. An extra couple inches of shaft doesn't make that much difference, does it, as far as overall swing weight?

 

http://www.scottycameron.com/custom-shop/about/Weight-Recommendations.aspx

[Salmon]

I have a feeling thats head weight. The longer the shaft the more weight in the shaft and therefore the less weight in the head to keep the weight consistant? At least that makes the most sense to me, it does not however translate that same for balance point.

[Blade]

The farther the head is from your hands, the heavier it feels when you swing it. Less head weight on a longer shaft will feel about the same as heavier and shorter.

[fozcycle]

Last year I purchased a 34" Nike Method Drone on sale with a head weight of 340 gm.......I got the 34" because they did not have a 33" but would order it for me.  So I used the 34" for two weeks waiting on the 33".   When i got it, the 33" had a head weight of 365 gm......which I liked the heavier putter better.  So does 1 inch begat 15 grams?