Dear All, More of the similar. Astute readers will note that we are up to the initial letter s, so unless I am beset by a flood of contributions from list members the 'Rules of thumb' series will soon cease. Thanks again for your help. Professionals: � Many professionals and freelance operators set their hourly rate by dividing their estimated annual income by one thousand. This covers things like the fact that free-lance people expect to put in one un-billable hour for every billable hour they do. Another approach is to decide what you think you can get away with charging, and then double it. Professionals reckon that their final expenses usually exceed their original estimate by a factor of two. Public address: � Use one watt (W) of amplification per person for an indoor audience and 1.5 W for an outdoor audience. Radius of the Earth: � The circumference of the Earth is about 40 000 kilometres, so its diameter is about 12 700 kilometres and its radius is about 6 400 kilometres. Reading: � Reading is easy for most people if the letters are 5 millimetres high at a distance of 500 millimetres. from this we get a ratio of 1:100, and this will work on any scale. If you are planning a billboard 40 m from a country road then the letters should be 400 millimetres high (40 m � 100 = 40 000 mm � 100 = 400 mm). Similarly, if you are designing a conference poster to be read from 2 m the letters should be a minimum of 20 millimetres high (2 000 mm � 100 = 20 mm). Refrigerator buying: � When you are buying a refrigerator allow 250 litres for two people plus 25 litres per person for each additional person. Rice: � When measuring dry rice in casseroles and soups allow as much as you can hold in one hand per person. You can hold between 60 millilitres to 80 millilitres in one hand, depending on the size of your hand (for me it's 80 mL per handful, but I've got large hands). This is enough for a serve of rice as a vegetable. If you are adding rice to a soup or casserole use the same amount as for a vegetable, that is allow one handful per person. You can test your own hand size using a measuring jug and taking an average of (say) ten handfuls. Rising air: � Air cools as it rises by about 1�C every 100 metres. Sinking air warms at the same rate. SAFE photography: � Check, in order, Shutter, Aperture, Focus, and Exposure. Scuba diving: � The average scuba tank holds enough air to dive for forty-five minutes at a depth of 10m. Scuba Diving: � To attain an appropriate buoyancy you calculate 10% of your body mass and attach this much mass to your belt, for example if you are 60 kilograms you will need an extra 6 kilograms. Cheers, Pat Naughtin 48 Roberts Road Belmont, Geelong 3216 Australia 61 3 5241 2008 [EMAIL PROTECTED] --
