I only saw Apostle smile once. It was Gauss' birthday, which he always celebrated in April with a cake. It had the Flux Theorem (Divergence to Surface Integral), and I got the "dx" labeled piece.

I complained that he had given me the smallest piece, and saw just the hint of a curl to his lips.

Hopefully, the "useful theorem"* didn't die with him...

*Apostle always referred to the useful theorem when proving problems in class... if you could figure it out, you were done.

Check out page 212, 1969 Big T (lower photo). Big smile. But yeah, didn't see that very often. Upper photo of him on that page is amusing also.

[1] http://resolver.caltech.edu/CaltechCampusPubs:20111101-15354...

That's actually a really cool link. Lots of photos of prominent CalTechers like Feynman and Gell-Mann that I haven't seen before (along with some of the former's artwork.)

I love the photo on page 219 of the engineering prof with his shiny new Tektronix 453 oscilloscope, which would have been exotic as hell back then. It's hard not to laugh at the idea of lighting up a smoke in a lab today.

I am tempted to believe that Lloydies had something to do with that 8^O...

We live for those we love and die.