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Certain conditions have to be observed, but, in general, it 
may be asserted that provided the models are to scale, that 
the height and length of the wave are to the same scale, the 
velocity of the wind being as the square root of the scale, 
or in other words, the corresponding depressions of the 
barometer in the same scale as the models — the behaviour of 
the model would be similiar to that of the boat. 
Thus, the behaviour of a model three feet long in waves 
two feet high, and with a wind twenty miles an hour, 
would correspond with that of a boat twenty-seven feet 
long in waves eighteen feet high, and a velocity of the 
wind sixty miles an hour. 
The main object of this communication is to point out 
that this similarity in the behaviour of models and larger 
boats under circumstances as regards the stress of weather, 
corresponding in scale to that of the models and boats, 
affords an opportunity of testing the sea-worthy qualities of 
the lifeboats in a degree that they cannot otherwise be 
tested. For, although the size of the boats does not preclude 
the possibility of their qualities being actually tested under 
any circumstances of sufficiently common occurrence to afford 
opportunities, yet the circumstances which call for the 
highest qualities in these boats, and in which the boats are 
most needed, are of extremely rare occurrence ; this appears 
at once, when it is considered that it is years since anything 
approaching such a storm as wrecked the two boats has 
been experienced, and that in order to submit any modified 
boat to a similar test, it may be years before there will be 
another chance, even if it could be made available when it 
did come. To make satisfactory tests on the full-sized boats, 
command is wanted of the extreme circumstances, and this 
cannot be had ; while on the other hand, to test the same 
qualities in their models, these extreme circumstances, 
modified to scale, are all that is wanted, and these are of 
such common occurrence as to afford ample opportunity, even 
if they cannot be commanded by artificial means. 
