238 LANKESTER, ON A MUSEUM MICROSCOPE. 
ledge of its nature. It has also been found necessary 
to write out a short label, giving directions how to adjust 
the focus of the microscope by the aid of the screw on the 
tube. Strangers to the instrument do not generally under- 
stand the way of throwing light on the object from the 
mirror below, and this should be done occasionally by an 
attendant. When it is known, however, exactly where the 
microscope is to be placed, the mirror might be fixed so as 
to require no further adjustment. With these precautions 
the instrument seems to have worked as well as I anti- 
cipated, and I hope that they may be erected in other 
museums; as there are, undoubtedly, a large range of objects 
equally interesting to the general public, as those seen by the 
naked eye, which can only be viewed by the aid of the 
microscope. 
The instrument described above is far from being as com- 
plete and convenient as it might be; but I have been 
encouraged to draw attention to it, in the hope that the 
directors of museums and instrument-makers may take up 
the subject, and thus render the microscope more available 
for popular teaching in science than it has hitherto been. I 
ought also to add that I understand instruments have been 
constructed to carry out the above objects, and that I hope 
this notice will serve to draw attention more generally to 
their construction and use. 
