Mr. W. J. Knowles read a paper "On the Classification of Arrowheads," recommending the use of the following terms: stemmed, indented, triangular, leaf-shaped, kite-shaped, and lozenge-shaped. Commander Cameron, the African explorer, mentioned that arrow-heads of the same shape as many exhibited by Mr. Knowles were in use in various African tribes. One shape was formed so as to cause the arrow to rotate, and was principally used for shooting game at long distances. The shape of the arrows varied according to the taste of the makers; in one district there were forty or fifty different shapes. Commander Cameron gave drawings of the men with horns, a tribe of which has been found by Captain J. S. Hay. According to the reproductions of these drawings by the illustrated papers, these horns are very prominent, and project forward from the cheekbone. Mr. Gwin-Jeffreys, whose experience in deep-sea dredging makes his opinion valuable, said that telegraph engineers did not sufficiently take account of the sharp stones on the sea bottom, but assumed too readily that they had to deal with a soft bottom only. Mr. John Murray of the Challenger expedition announced that meteoric dust is found in the sea ooze, a result that follows as a matter of course from the discovery that this cosmic dust is falling all over the earth. AN ENGLISH CROP. The yearly trial of harvesting machines was made this year at Leamington, and the rye grass field, where the reapers and mowers were worked, has its history given in the "Engineer," London. "It will be interesting if we first describe this rye grass crop and the preceding crop. A crop of wheat was grown in this field of seven acres last year, and by the end of September it was well cultivated and sown with rye grass seed. Three crops before this have been cut this year, the weight of which was about eight tons to the acre for each crop, and as the selling price was 1s. 6d. (36 cents) per cwt., this was at the rate of £12 ($60) per acre per crop, or £36 per acre for the three crops. Had not the last crop been set apart for the reaper and mower trials, it would have been cut three weeks ago, when there were again about eight tons to the acre. As it was, however, last week the crop had gone too much to seed, and was too much laid for being of prime quality; the result of which is, Mr. Tough, the owner, reckons the plants are too much spent to stand well through a second year, and he therefore contemplates turning it over in the spring for mangolds. Mr. Tough calculated, however, that there were ten tons to the acre this cut, and lots of carts and vans came to take the best of it; that is, the parts which were not laid and yellow at the bottom, at the same price, 1s. 6d. per cwt. The carts are weighed in over a weigh-bridge, and weighed out again after the buyers have loaded up as much as they choose or require. We may add this is better than selling by square measure. As to the next growth, Mr.