GUEST,Boab's "All info as much use as an ashtray on a motorbike---"
reminded me of two that are common around where I live:
"Useless as tits on a bull" and "Useless as a plough upstairs".

The continuing posts about cannon balls and brass monkeys is intriguing for a couple of things:
1 Everybody, with the possible exceptionof one poster who made reference to Brighton and Aberdeen, seems to have associated cannon and their ammunition with ships (and the Victory seems central to many notions) when there is plenty of evidence (ie stories) about land-based use of them,
2 Everybody, again with the possible exception of the poster who started the reference to monkey's tails and other anatomy, seems to give little credit to the possibility that much earlier people had the same sense of absurd wit that we value, exemplified in the more modern Goon Show; the absurdity of linking the feeling of bitter cold to both balls and a brass monkey is exquisite.

But to add to the list, a couple from the days of cutting tall timber manually.

"Top notch" is used to describe "the best" and there are two situations where it applied literally. The tallest trees in Australia's forests (and the one measuring 366' when felled was regarded as the tallest in the world) are Eucalyptus regnans and had very large buttresses (my grandparents had a piccie of the base of one that took 39 blokes to stretch arms to reach around it) that reached a good 40' up the trunk from the ground. To fell the tree and have a log that was round, two axemen would operate from opposite sides cutting a notch as far up as they could reach. Into the notch they'd ram a 6' long horizontal plank, climb onto it with their axe and another such plank and stand on it to cut another, higher notch. This would be repeated until they got to the desired height when they would fell the tree. Woodchop competitions still celebrate this technique. To get to the required height the fastest was to be top notch.

The other situation was when the log was being sawn longitudinally and gave rise to another expression often used in Australia. Before mechanical milling, the log that was going to be sawn was positioned over a pit and sawn by two men pulling the opposite ends of a long saw; crosscut saws (with a particular set to the teeth; another 'term') were used when cutting across the log and rip saws (with a quite different set to the teeth) were used for cutting along the log.

The "top dog" would stand on top of the log and place the rip saw in the top notch where the cut was to start. The "under dog" would stand in the bottom of the pit and pull the saw down. The top dog would then pull the saw back up but, to maintain rhythm and speed, would not bite the saw into the timber as hard as the under dog could when using gravity to assist his pull down. The underdog also got covered in sawdust from all this, as well as doing the tougher labour.

Cheers, Rowan