I’ve never had any problem with slides before so I’m not sure why now but in a tune I’m practising I’m faced with going from Fsharp to A with a slide on the A and don’t feel I can stop or tongue an intermediate G. So how does one slide smoothly legato-style between these two notes? Any thoughts?
Basically two ways: serial or parallel.
Serial: Start sliding the F# to G. And before you’re done and the hole is fully open, start sliding the G to A. Then finish the G to A slide normally. Voilà. You won’t hear an intermediate paused G along the way. That’s what I’d usually do.
Parallel: Slide both fingers at the same time. But each finger needs to slide more slowly, because you’re opening up a larger “virtual hole” (i.e. 2 holes). It’s a bit harder to control, and there’s more chance of a pop or squeak as the upper hole opens. But it can also work well, depending on how your particular whistle responds.
… or you can fool the ear into hearing a slide between those two notes, either by starting the slide up from the F# and then just jumping to the A at an appropriate and timely point, or start on the F# and jump to an already sliding finger from the G up to the A. Done well, either of these can give the illusion of a full glissando between the F# and the A. It’s what fiddlers do (whatever they tell you 
).
That reminds me of those (famous?) glisses in the middle of Yours Is No Disgrace by Yes (The Yes Album). Conveniently, here’s a clip of the exact spot (courtesy of allmusic.com):
http://rovimusic.rovicorp.com/playback.mp3?c=kMYO1hcfAmp-WkiY3WZehfQIxMnXLaW9NvEpt_rvU6E=&f=J
This is also a great test to be sure that your Left and Right speakers are hooked up correctly. 
Actually, Mike, here’s third way (in addition to my 2 above): Leave the F# finger (B1) planted down, and slide the G finger (T3) up to the A. Then lift the B1 finger off, to prevent the A from sounding too veiled. The same caveats apply as the parallel method, but it can be done if you’re careful.
Exactly. They sound good to me. 
Wow! Thanks for the thorough and indepth thoughts . . . more than I could ask for.
Start sliding the F# to G. And before you’re done and the hole is fully open, start sliding the G to A. Then finish the G to A slide normally.
Just checking, MT. Do you mean finish the G to A slide normally or did you mean to put the F# to G. If not then what happens to the F# to G slide after starting it?
Can’t wait to test these options out.