On being the right size

To: 'Canberrabirds' <>
Subject: On being the right size
From: Geoffrey Dabb <>
Date: Mon, 7 Mar 2022 22:25:13 +0000

Thank you Martin for locating the famous essay.  Yes, that’s the one.  I particularly remembered the mouse falling down the mine-shaft.  And the rat, the human and the horse, with such different results.  Size is so important to birds.  We can understand, more or less, why a Yellow-tailed Black-Cockatoo is that particular size, but why is a Swift Parrot that size? The cockatoo now has the evolutionary disadvantage of having to find large nest hollows, so if it was being designed now it would be a different size, like so many other things. Size relates to conditions at a particular time.  Our TV screens are now much larger, but cars, radios and household dogs much smaller.


I mentioned the essay as a clue to the graphic item. This was intended to invite two or three steps in logic, but Philip got there in one. The graphic could be made any size digitally. (Or it could be projected on the side of the opera house, as so much graphic material is these days.)  If the apparent size was larger, it would be obvious to the older chatline subscriber that the small coin was a penny. ‘What is  penny?’, some will ask.  That is a long story,  but sufficient to say it is an obsolete coin much larger than $2.  It would be clear that at least 2 of the 3 items are the wrong size in relation to one another. Curiously it is the size of feather that will indicate which coin is the ‘right’ size (assuming that one is).  Philip had an advantage here, being able to ID the feather.  The penny is the ‘right size’, so it is quite a large feather, 510mm in length.  Incidentally, the Griffith/Narrabundah peafowl are on average smaller than those found elsewhere, but that is another story.   



From: Philip Veerman <>
Sent: Monday, 7 March 2022 10:24 AM
To: 'Geoffrey Dabb' <>; 'Canberrabirds' <>
Subject: RE: [Canberrabirds] On being the right size


Well before having read that article, though skimming through I am of course familiar with the intent, I think there is some trickery in the graphic, comparing a penny with a $2 and what I suspect is a peafowl feather, I think from a left side of tail. The $2 is a curiosity, as you can’t play 2 up with it, as both sides are heads. You theme might be heads & tails.


From: Canberrabirds On Behalf Of Geoffrey Dabb
Sent: Monday, 7 March, 2022 9:26 AM
To: Canberrabirds
Subject: [Canberrabirds] On being the right size


When I was at school, more than 60 years ago, this essay  by JBS Haldane was in one of our schoolbooks.  I see that it is now sufficiently famous to be covered in Wikipedia.  (I must quickly reject any inference that I think everything, or even most things, covered in Wikipedia are appropriately described as famous.)


From long experience I know that some mystery surrounds the question when a graphic qualifies as the ‘right size’ to enable reproduction on this chatline.  No matter, that is simply a test of one’s perseverance. Many offerings have been regarded as of insufficient importance to justify even a second attempt.


With respect to the below, this is a fourth attempt. That is not an indication of importance, given the trivial nature of the graphic.  I was simply testing the properties of the current filter, which do vary from time to time.  Now that I have (possibly) inflicted it on you, my question is whether anyone has thoughts on the subject matter.


A coin next to a coin

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