the rear has passed.  A “wild” engine running very slowly might not actuate the signal as long as was desirable, but even then it is not unreasonably claimed the warning would probably last long enough for all practical requirements, as a team approaching a crossing at eight miles per hour takes 42 seconds to go 500 feet.  All the bearings of any importance are self-lubricated by oil cups, the whole apparatus being designed to require inspection not more than once a month.  The iron case when shut is water-tight, and when duly locked cannot be maliciously tampered with without breaking open the case; so that, the manufacturers claim, it will not be essential to examine it more than once a month.  The parts outside the case are all strong and heavy, and not likely to get out of order, while easily inspected.

The apparatus can be used for announcing trains as well as sounding alarms, as the gongs can be placed upon any post or building.  The gong has a heavy striker, and makes a great deal of noise, so that no one should fail to hear it.—­Railway Review.

* * * * *

THE SIZES OF BLOOD CORPUSCLES.

Professor Theodore G. Wormley, in the new edition of his work, gives the following sizes of blood corpuscles, as measured by himself and Professor Gulliver.  We have only copied the sizes for mammals and birds.  It will be seen that, with three or four exceptions, the sizes obtained by the two observers are practically the same: 

    Mammals Wormley.  Gulliver.

Man                    1-3250        1-3260
Monkey                 1-3382        1-3412
Opossum                1-3145        1-3557
Guinea pig             1-3223        1-3538
Kangaroo               1-3410        1-3440
Muskrat                1-3282        1-3550
Dog                    1-3561        1-3532
Rabbit                 1-3653        1-3607
Rat                    1-3652        1-3754
Mouse                  1-3743        1-3814
Pig                    1-4268        1-4230
Ox                     1-4219        1-4267
Horse                  1-4243        1-4600
Cat                    1-4372        1-4404
Elk                    1-4384        1-3938
Buffalo                1-4351        1-4586
Wolf (prairie)         1-3422        1-3600
Bear (black)           1-3656        1-3693
Hyena                  1-3644        1-3735
Squirrel (red)         1-4140        1-4000
Raccoon                1-4084        1-3950
Elephant               1-2738        1-2745
Leopard                1-4390        1-4319
Hippopotamus           1-3560        1-3429
Rhinoceros             1-3649        1-3765
Tapir                  1-4175        1-4000
Lion                   1-4143        1-4322
Ocelot                 1-3885        1-4220
Mule                   1-3760
Ass                    1-3620        1-4000
Ground squirrel        1-4200
Bat                    1-3966        1-4173