KEENNESS OF SCENT IN DOGS.
[To THE EDITOR OF THE "SPECTATOR.'
SIR,—Every one knows the wonderful keenness of scent which dogs possess, and many illustrations of this will recur to your readers, but it would be interesting to have authentic evidence of the range of this remarkable faculty in our canine friends. The following experiment may be worth recording in this connection. I have a little Yorkshire terrier, ' Mick,' which is in the habit of fetching any object I throw for it to run after; if I take a piece of stick, mark it, and bury it in a pile of other sticks, Mick' will invariably find out by its nose the piece I have held for a moment, and bring it to me. It will do the same with any particular pebble thrown in a heap. In front of the country cottage at which I have been staying this summer is a short carriage drive entirely covered with rather large pebbles ; the number per square foot I found to vary from fifty to one hundred and fifty or more. As the space so covered was some six hundred square feet, there were roughly from thirty thousand to one hundred thousand pebbles to select from, and therefore the odds were at least fifty thousand to one against any particular pebble being selected. If, however, I picked up one of these:pebbles, marked it, and then threw it down, Mick,' when told to " find," would invariably discover the right stone, though not allowed to see where it had fallen, and though afresh stone was used eaohjtime. It has done this often six to ten times running without a break ; the odds against the success being due to chance coincidence are therefore many hundreds of millions to one, so that this explanation may be rejected in limine. It did not matter whether the stone was thrown when the dog was kept com- pletely out of sight, or whether it was daylight or a pitch- dark night; so long as Mick' knew what he had to do, he never made a mistake; it is true that occasionally he failed to find the stone, but he never brought a wrong one. Ha would traverse the ground, sniffing over the surface, and if after searching for a minute or so he failed to hit the scent, he generally came back to me for further instructions. Even holding the stone in my hand for the shortest time in which it was possible to do so, just sufficient to pick it up and throw it down, was enough to impart a scent which the dog could detect. That it was not a question of difference of temperature given to the stone by momentary contact with the hand was shown by holding a stone in a gloved hand till it was slightly warm, when the dog was unable to find the stone, even when led to the spot where it had fallen. Had it clearly associated the scent of the glove with me it would doubtless have been successful, for it can find which way I have walked by sniffing out the track of my boots. After some minutes the scent gets too weak for the right stone to be found, and in any case it cannot be detected beyond a distance of a few inches, so that 'Mick's ' nose has to traverse the ground to and fro very rapidly and completely before he can bit the trail. As the stone must have derived some minute portion of matter from my band to enable its position to be detected by the dog, the sensitiveness of this faculty of smell rivals that of our most refined chemical or optical methods of detecting traces of matter. I relate these simple experiments in the hope that some of your readers may be able to give other still more striking and authentic instances of the sensory powers of dogs and other animals —I am, Sir, &c.,
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