Scientific.

Waikato Times, Volume XXVIII, Issue 2286, 5 March 1887, Page 2 (Supplement)

Scientific.

Tun Delicacy ok the Sknse ok Smell. '['he delicacy of tho sense of smell in the dog, the shark nud insects is well recognised. Man is not greatly drifted with tho olfactory sense compared with these ; but, if we mny place reliiinoe on the experiments of Professor Valentine, the delicacy in fairly grout even in human beings. If we can sniff a tenth of a pint of air containing bromine in the proportion of a thirty-thousandth of a milligramme, or tho same quantity of air impregnated with the two-millionth of a milligramme of sulphuretted hydrogen, we cannot mathematically have ground of

complaint agaiust our olfactory sense. Still less can this be the case if we can, as seems likely, detect tho 230*milliouth of a milligramme of sulphuretted alcohol or mercaptan. —Lancet. A Standard Metronome.— M. SaintSaens has suggested to the French Academy of Sciences that it should undertake the work of providing a standard or normal metronome for the benefit of musicians and musical art. The Academy

lias already rendered an important service to music by the establishment of the normal diapason, and as the metronomes now employed are not standardised or uniform it would be an additional service if the Academy also constructed and issued a' standard instrument, while requiring that those in use should be made to agree, with it. The .metronome was invented at the end, of last century by Stoeckel and perfected toy Maeizel ; and though universally employed it i.s by no means well regulated. —Engineering. Electkic Travelling.—M." Julien, a distinguished engineer, of Brussels, has succeeded.in storing.a sufficient quantity of electricity under the seats of an ordinary tramcar to travel a distance of 25 miles without rene'wing the motor power. By this invention, all the cumbersome details of other systems have been abolished: the electricity in previous instances was connected with the permanent way, the current being transmitted through wires and by a rod with the car. M. Julien 8 vehicle moves forward gracefully like a thing of life ; it is independent of all extraneous contrivances, and there is a total absence'of jolting. This opens a new era in electric travelling. To Tbst Steel.—Pour on the object to

be tested a drop of nitre acid of 1.2 sp. gr., let it act for one minute, then rinse with water. On iron the acirl will cause a whitish-gray, on steel a black stain.