  Torsional oscillator (TO) is an experimental technique which is widely used
to investigate superfluid responses in helium systems confined in porous
materials or adsorbed on substrates. In these systems, heat capacity (HC) is
also an important quantity to study the local thermodynamic properties. We have
developed a simple method to incorporate the capability of HC measurement into
an existing TO without modifying the TO itself. By inserting a rigid thermal
isolation support made of alumina and a weak thermal link made of fine copper
wires between a standard TO and the mixing chamber of a dilution refrigerator
in parallel, we were able to carry out simultaneous TO and HC measurements on
exactly the same helium sample, i.e., four atomic layers of $^4$He adsorbed on
graphite, with good accuracies down to 30 mK. The data reproduced very well the
previous workers' results obtained independently using setups optimized for
individual measurements. This method is conveniently applicable to a variety of
experiments where careful comparisons between results of TO and HC measurements
are crucial. We describe how to design the thermal isolation support and the
weak thermal link to manage conflicting requirements in the two techniques.
