Masthead and hounds - a puzzlement

[airborne1]

Hi, The other day I stipped my mast and encountered a puzzle.
The boat is a Luke 5-tonner, built in 1949 and has a wooden mast.
Rig is shown on this photo:
http://boatsandsailing.fotopic.net/p38282026.htm
My puzzle is the mastheadand hounds arrangement.
The arrangement I found is shown in the following photo:
boatsandsailing.fotopic.net/p38282027.html
and
boatsandsailing.fotopic.net/p38282028.html

Hope these photos work as I don't know how to get them to show directly in the post.

What I would like to know is - what is the reason that the top of the mast has two smaller diameters. I did expect a single smaller diameter so that the shroud soft-eyes could be looped over it but why the even smaller diameter at the top of the mast. They seem to have been cut on a lathe as they are well formed and so I assume that they were put there at build time.
Another puzzle is why the intermediate diameter is so long, surely it doesn't need to be much longer that required to accept 5 soft-eyes.
Does anyone have any explanations for this arrangement.

I want to keep the boat/mast as traditional as possible but if no one can expain the purpose of the two diameters then I will try and bring the mast up to date in an aesthetic manner as possible.
Thanks and I hope the question is meaningful as I am trying to be.

 

[Roach1948]

What sort of rig is she?

An idea might be that it was a recess for an Anchor light - I had that but on a turned extra bit of mahogany at the masthead - the anchor light fitting "squidged" into the turned recess.

 

[airborne1]

Sorry all, forgot to mention she is a Bermudan Sloop fractional rigged mast.
Roach, sounds reasonable until you have seen the mast for real. There is some wear in the intermediate diameter but no recess such as you suggested.
Thanks anyway

 

[fluffc]

The smaller diameter section at the top of the mast is for a 'button'. This is a decorative trim piece, in the shape of a donut with a vertical inner face.

As to why the long bit is so long - mine is the same - but maybe Irish 'to be sure to be sure'...

 

[donm]

I could not pick up the photos. I was moored alongside a Luke 5 tonner for several years in the seventies. She had a seven eighths rig with jumper struts at the hounds to the masttop, and running backstays.