The 'road to nowhere': the evidence for travelling criminals

A combined visual and electronic liquid indicator which may be used as a battery hydrometer is disclosed. An outer housing of a generally cylindrical shape receives a centrally located elongated light transmitting viewing rod. The lower portion of the rod extends into a channel at the lower end of the outer housing. A float is retained in the channel by a retaining cage. A second generally cylindrical inner member which fits over the rod and into the outer housing has a light sensor and a light detector secured at its lower end across diametrically opposite portions of the float channel, and the outer housing and the inner member are then sealed together.