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“The angle of friction was found to remain constant until a certain stage of the loading, when it suddenly fell to about half of its original value.  It then remained constant for further increases in the load.

“These results, which confirmed those obtained previously with less satisfactory apparatus, are shown in the table below.  In the first column is shown the load, i.e. the weight of sleigh + weight of shot added.  In the second and third columns are shown, respectively, the coefficient and angle of friction, whilst the fourth gives the temperature of the ice as determined from the galvanometer deflexions.

Load.  Tan y. y.  Temp.

5.68 grams.  0.36+-.01     20 deg.+-30’    -5.65 deg.  C.
10.39                                -5.65 deg.
11.96                                -5.75 deg.
12.74                                -5.60 deg.
13.53                                -5.65 deg.
14.31                                -5.65 deg.
15.10 grams. 0.17+-.01    9 deg..30’+-30’  -5.60 deg.
16.67                                -5.55 deg.
19.81                                -5.60 deg.
24.52                                -5.60 deg.
5.68 grams. 0.36+-.01      20 deg.+-30’    -5.60 deg.

“These experiments were repeated on another occasion with the same result and similar results had been obtained with different apparatus.

“As a result of the investigation the following points are clearly shown:—­

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“(1) The coefficient of friction for ice at constant temperature may have either of two constant values according to the pressure per unit surface of contact.

“(2) For small pressures, and up to a certain well defined limit of pressure, the coefficient is fairly large, having the value 0.36+-.01 in the case investigated.

“(3) For pressures greater than the above limit the coefficient is relatively small, having the value 0.17+-.01 in the case investigated.”

It will be seen that Morphy’s results are similar to those arrived at in the first experimental consideration of our subject; but from the manner in which the experiments have been carried out, they are more accurate and reliable.

A great deal more might be said about skating, and the allied sports of tobogganing, sleighing, curling, ice yachting, and last, but by no means least, sliding—­that unpretentious pastime of the million.  Happy the boy who has nails in his boots when Jack-Frost appears in his white garment, and congeals the neighbouring pond.  But I must turn away at the threshold of the humorous aspect of my subject (for the victim of the street “slide” owes his injured dignity to the abstruse laws we have been discussing) and pass to other and graver subjects intimately connected with skating.

James Thomson pointed out that if we apply compressional stress to an ice crystal contained in a vessel

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