494 
Analyses of Books. 
[August, 
engineers hold that no bridge has been exposed to more than 
30 lbs. per square foot. Yet the Committee on the Tay Bridge 
disaster state that at Bidstone, near Liverpool, a pressure of 
90 lbs. per square foot was recorded, and on another occasion 
77 lbs., and at the Oxford Observatory the pressure in the storm 
of October 14 was found as high as 53 lbs. The probability is 
that the pressure of the wind in tempests varies, not merely from 
moment to moment, but in point of space from square foot to 
square foot. So that supposing the pressure upon a square foot 
is registered at 40 lbs., it does not follow that a building expos- 
ing a surface of 40 feet by 30 feet would have to bear at any 
moment a pressure of 48,000 lbs. 
Mr. S. H. Swayne gives a few remarks on the carnivorous 
“ owl-parrot” of New Zealand, Nestor notabilis. The writer 
suggests that if this species continues to exist and maintain its 
carnivorous propensities, it may possibly develope into a 
decidedly raptorial bird. We fear that this interesting experi- 
ment is not likely to be tried. 
Professor Ramsay communicates a most interesting memoir 
on the sense of smell. After contending that four of the senses 
— six in number if we include, as we fairly ought, the recogni- 
tion of heat — are in all probability mediated by vibration, he asks 
whether smells are excited by liquids, solids, or gases ? The 
two former states of matter being excluded experimentally, gases 
and vapours only remain. He considers that the property of 
smell is confined to some elements only. Substances which 
have no smell, or which are merely irritating when inhaled, have 
all low molecular weights. Among the carbon compounds, in- 
crease of molecular weight produces, to a certain point, smell. 
This the author exemplifies by several instances, such as the 
alcohols. Pure methylic alcohol he declares inodorous, “ ethylic 
alcohol, when freed from ethers, has a faint smell, and the odour 
rapidly becomes more marked as we rise in the series until the 
limit of volatility is reached, and we arrive at solids with 
such of low vapour tension that they give off no appreciable 
amount of vapour at the ordinary temperature.” Prussic acid, 
we learn, is not smelt by more than four persons out of every 
five. 
A further conclusion is that smells are generic. Thus chlorine, 
bromine, and iodine, besides their specific differences in smell, 
have a something common to the whole group, which may be 
called a haloid smell. Very similarly sulphur, selenium, and 
tellurium, in combination with hydrogen have a generic odour. 
In like manner various generic groups of smells may be traced 
among the carbon compounds. 
The tendency of a rise in the series is to make the smell 
“ heavier,” less etherial, and more characteristic. 
As a theory of the sense of smell, which is hitherto a desidera- 
tum, Prof, Ramsay suggests tentatively the following. “ There 
