I forgot to say that I'm getting the following error with that code:
sketch_nov15a:28: error: cannot convert 'MAX6675::readCelsius' from type 'double (MAX6675::)()' to type 'double'
double T1 = ktc.readCelsius;
^
sketch_nov15a:29: error: cannot convert 'MAX6675::readCelsius' from type 'double (MAX6675::)()' to type 'double'
double T2 = ktc2.readCelsius;