I AM mystified as to why a supposedly intelligent person such as York student Sam Hall would have wished to prove a point by dropping a live mouse from a height of 25 feet (November 26).

I was pleased to see the York University Students' Union, the university's head of communications and the local RSPCA were up in arms.

I would feel much more respect for these people if they at least expressed some concern for the many animals experimented on annually at the university and at its various science park spin-offs, also in the name of spurious experiments.

Alan Robertshaw,

York Animal Aid,

Towthorpe Road,

Haxby, York.

...IN response to your "Danger Mouse" story about a York student's plans to drop a mouse off of a tall building, I believe his physics are correct, but he has not considered other factors.

Given an infinite time to fall, all objects will reach the same "terminal velocity", but over these relatively small distances, there are two factors coming into play: the effects of gravity acting on the mass of the animal (which is in proportion to the animal's area), and the slowing effect of the air, or friction, which is proportional to the flat underside of the animal.

In other words, a cube measuring 2cmx2cmx2cm would have a volume of 8cm3, and a flat surface of 4cm2, a ratio of 2:1. A cube measuring 4cmx4cmx 4cm would have a volume of 64cm3, and a flat surface of 16cm2, a ratio of 4:1, and therefore land with much more of a bang.

To put this in animal terms, if you were to drop animals of roughly the same ratio of dimensions, such as a mouse, a cat and a horse, the mouse and cat would have much less messy endings than the horse.

However, he has failed to take into account ability to land. Cats have not only evolved to have strong legs, but have also learnt to use them to fall properly. Therefore a cat falling out of a first floor window would probably be fine.

But the lack of day-to-day opportunities to fall great distances means that mice haven't developed this ability.

I recommend either dropping the mouse on to something soft, such as a cliff with a sandy beach below, or much better, dropping a mouse-sized object to prove the point.

John Taunton,

Rawcliffe Lane, York.

Updated: 11:41 Friday, November 28, 2003