1/2? 
I bought an extra tube for my Bracker high D. But I intend to get a head-joint for it at some point. Then that will make 14.
Quantity should be weighed against quality. I have neither.
I have a bit o’ quality, but it’s still a short list…
Burke aluminum high D
Burke brass B
Clarke Sweetone tweaked
Copeland nickel high D
Copeland nickel high C
Copeland brass low F
Generation high D
Guido Gonzato A
MK low D
New Kerry low D
Overton low Eb
Oz high D
Sindt high Eb
Tilsbury Bb
Walton ‘Little Black Whistle’ high D tweaked
Walton ‘Mellow Dog’ C/D set tweaked
Not a long list, but a nice list. Still a few keys missing, but they’ll fill in eventually.
Point of order. Does a C/D set count as one or two whistles?
Per R Small above, 1 1/2…
Best wishes.
Steve
Assuming by “set” you mean one head, two bodies, I would count it as 1 1/2 because it’s not two complete whistles.
I’m not sure I agree with this. I only have one mouth, therefore, I can only play one whistle at a time. I can choose to play the Mellow Dog D or I can choose to play the Mellow Dog C. Whichever I choose, it’s a different whistle from the other.
I can stir up trouble in many keys. 
But we aren’t talking about how many whistles you can play at one time. We’re talking about how many whistles you have, period.*
*At least, I was. 
Over what period?
Feadoggie
And if you ask me to play a Mellow Dog D, I have it. Same if you ask me to play a Mellow Dog C, I have it.
But here’s where I think you run into trouble… what if someone has a D-C-Bb set sharing one head? Are you going to count that as 1 2/2?<—rhetorical and silly
It’s certainly not 2 whistles according to your previous comment (“I would count it as 1 1/2 because it’s not two complete whistles” -Whistlin’ Will) since it’s not two complete whistles, and it’s certainly more than 1 1/2. So you either have to count it as 3 or count it as 1 2/2. Did I mention that “1 2/2” is silly?
The defense rests.
Okay, I see where we’re going with this. I was thinking of a whistle as adding up the heads (1/2) and bodies (1/2) to get a sum, which would be the number of whistles you have (i.e. from a more mathematic point of view) where you were looking at it from a more practical point of view (i.e. as a head plus a body equals a whistle). If this makes any sense at all, which it probably doesn’t. But I agree with you, JTC111.
So, if you have something like a D-C-Bb set with one head between them, then you can count that as three whistles.
(But wait, suppose you had a friend who needed to borrow a whistle at the same time you needed a whistle… 
No, no, let’s just let that debate die a quiet death.)
I am not in the running. First of all I don’t count them. I propose octaves as a unit for whistle quantities as in I have about 7 or 8 octaves of whistles. I have a complete set of brass Gens and a complete set of nickel Gens plus a few extras. Then there are the Albas, Burkes, Clares, Clarkes, Dixons, Feadogs, Feadans, Hoovers, Howards, Humphreys, Jubilee, JudyK, Kerrys, O’Briains, Susatos, Waltons, Water Weasel.
As you can see there are many brands I do not have. However I have a wish list.
You may not be in the running, but we are definitely part of the same tribe…and what’s a JudyK?
Philo
PhilO, the JudyK was a very limited production whistle that was never sold but given as gifts. I never kept count, but suspect there are less than 2 dozen in existence. Some were nice, some decent and some probably not so hot … but the price was right. 
JudyK
How about a “chord” of whistles? A chord is a grouping and…that way your chord of whistles could be augmented or diminished.
Would a “chord” have an exact value, like 10 or 50?
I see “chord” is getting some interest. I have no idea if a chord would have an exact value. I don’t even know what that means. Music theory wasn’t big on my list of things to learn. Why learn theory when another instrument could be learned instead? Any talk of music theory gives me a headache.
I think a chord of whistles would be 128 cubic feet
Ron
Only if they are wooden whistles??
Best wishes.
Steve