Just to answer a few questions about this revolutionary piece of equipment.
How long should the piece of string be?
Actually, it has to be made precisely the correct length for the part of the world you live in.
For an area that suffers from strong winds, it doesn't need to be too long as you could end up hanging yourself, as the wind blows it everywhere, or to counteract that effect, a one pound weight on the end may cure the problem. But that is only a theoretical assumption, field trials should give more understanding of what is really required.
For wet or dry countries, for wet, you can have it much longer, as the drips will easily reach the end, but say in a desert region, a lot shorter, otherwise you will be waiting forever for the drips to get to the bottom to drop off.
Ah, but there needs to be a pivoted clamp and pivot arm. Otherwise how would you hold it or invert to check for freezing?
It has been found during field trials that the thumb and forefinger is perfectly adequate for a portable version of this instrument, and it has also been found that either left or right hand digits can be used without any detrimental effects to the readings obtained. The use of gloves in such a cold environment is thoroughly recommended, as removing string from between frozen to it digits can be rather painful.
One major point regarding safety must be raised (the dreaded H&S). If the area to be checked is both freezing AND windy, special care must be taken to keep a vice like grip on the instrument. There are cases where people and objects have been impaled by lengths of frozen string.
For lab work, a small crocodile clip has been found perfectly adequate, if wind speeds are kept fairly low.
Bogs
BTW, do you really want to keep all this bullsh going?