Ability to access this website
does not imply a contract with David Knight or any of the other
contributing authors. The information accessible from this website is
offered without warranty of any kind, and I reserve the right to
withdraw the service without notice. While every effort has been made
to ensure that the information given here is correct, no liability is
accepted for accident, injury, loss, inconvenience or disappointment
resulting from its use.
David W Knight
sign seen by people entering the town of Ottery St Mary on tar barrels
night relates to the nature of the evening's events; but it is also of
general existential relevance.
Some of the experiments and activities described in this website are potentially dangerous.
Although safety issues are typically discussed as they arise; it is
assumed that anyone attempting to repeat any of the procedures
described will be fully conversant with (and where necessary will have sought training in) the relevant safe working
Some dangers are not immediately obvious:
1) Skin and (particularly) eyes must not be exposed to hard UV light
(such as is produced by silica-walled mercury discharge tubes).
2) Glass vacuum equipment must never be operated without safety
glasses. Unless provided with an implosion shield, large glass vacuum
chambers should not be operated without a full face shield and full body
3) Audiences, bystanders, and passers-by require the same protection as
4) The use of SCUBA diving equipment requires tuition by trained and properly certified instructors.
5) Modern batteries of high energy density can be dangerous. Old
fashioned car batteries can be bad enough; but Lithium Ion batteries
should never be shorted-out, mistreated, or charged close to places
where people sleep.