OVER 2 YOU, 074 (02/04/02)

GETTING A BEARING

It should be possible to compute bearings and distances on Ordnance Survey maps by just entering the six figure map references of start and finish points.  Does anyone know how?  Do I need a program or just a formula?
Cliff Mallinson, North Somerset

You do not need a special program but the following works with Excel. Enter the start and finish map references as six figure values.

The bearing is given by:

=MOD(DEGREES(ATAN2(MOD(finish,1000)-MOD

(start,1000),INT(finish/1000)-INT(start/1000)))+360,360)

This, of course, is a Grid bearing; it may be necessary to convert it to a True bearing or a Magnetic bearing.

The distance, in metres, is given by:

=SQRT(((MOD(finish,1000)-MOD(start,1000))

^2+(INT(finish/1000)-INT(start/1000))^2))*100

Alex Duffus,

It is quite easy to obtain the distance between two points on an OS map, an old Greek chap called Pythagoras gave us the formula some time ago.

First get the differences between the coordinates

diffEastings = Val(Eastings2) - Val(Eastings1)
diffNorthings = Val(Northings2) - Val(Northings1)

Then use Pythagoras to get the hypotenuse

Result = Sqr((diffEastings ^ 2) + (diffNorthings ^ 2))

Where Sqr is the square root and Caret ('^') represents 'raised to the power of’. This formula can be condensed down easily and put into a single cell in a spreadsheet. Taking the bearing is more complex and involves obtaining the Arctangent of the ratio of the distances.

Angle = Atn(diffEastings / diffNorthings)

However, this only gives the correct result if the direction is to the North-east.  You will have to add a factor to turn the angle in the right direction.  Also the chances are that the function Atn will return the angle in Radians, so you will have to multiply the result by 57.29 to get the bearing in degrees.  (I have a little program in VB6 that does this)  A further function will give the angle in mils.

This is the basis behind much map-making software, but it also has to borne in mind that if you went out with a theodolite and measured the true distances, you will have allow for the differences between OS Grid North, True North, the curvature of the Earth and the minor distortions present in producing a flat map.  Also GPS may not accurate enough for what you may be planning. I still maintain that a pair of dividers and a protractor may be quicker...

Matthew Williamson, Hounslow, Middlesex

A quick trawl on the net revealed a website at: www.andyholden.freeserve.co.uk, which contains a bearing and distance calculator, albeit only for users of Microsoft's Internet Explorer. Just enter the numbers and click the button.

Alex Cartwright,

Try http://www.multimap.com if you enter start and finish postcodes you will not only get distances but a map as well.

Roy Wiggins,

If Mr Malinson is happy with accuracy of better than 1 in 2000, then he can treat the 6 figure reference of a point as its distances in metres to the east and north of an arbitrary datum, and can do the calculations on a calculator.   If the references of the two points are E1, N1 and E2, N2  then the distance between them is Square root of  {(E2 - E1) squared + (N2 - N1) squared}

It is usually convenient to divide all the references by 1000 before putting them into the formula as this will give the answer in kilometres and will avoid over-reaching the number of digits the calculator can deal with.

For bearings, the formula is: Arctan {(E2 - E1) / (N2 - N1)}.  If  (N2 - N1) is negative you have to add 180 degrees and if the answer still comes out negative you have to add another 360. This gives bearing relative to grid north, but the local difference between grid north and true north, typically up to about 2 degrees is given on the OS Landranger maps.

For surveying accuracy he should see the Ordnance Survey paper The Ellipsoid and the Transverse Mercator Projection, which gives the necessary formulae.

Ken Brown, Portishead, Bristol

USING OLD PCS

I have a small collection of four PCs, from 386 to Pentium 1, all of them perfectly serviceable but woefully out of date by current standards. I have promised them to my son’s school and a local charity shop – not that either seemed terribly impressed -- but I was wondering if anyone could come up with a suggestion for using at least one of them in a practical way, doing something around the house, even if it’s only switching the pump in my fish pond on and off? I would like to get back just a little of my initial investment

Doug Steele, via email

I use a 233 MHz PC as an audio recorder, recording 24 hours per day in MP3 format. This makes a file of 1.3Gb for 24 hours. I record classical music but of course anything that goes into the soundcard can be recorded even a microphone that could be used for security purposes, birdsong etc. One can easily slice out the recording the parts that are required. All the software required is freeware. 

Derek Horton,

Doug Steele might be interested in this site, which I found at: http://www.oldcomputers.cjb.net.  Be careful of the Active X window, which opens automatically

Sandra Worden,

CHESS CHAMPIONS

We read a lot about chess grand masters playing powerful computers, but has anyone pitched commercially-available chess programs against one another, and if so, which one won?

Jane Knight, via email

My fourteen-year-old son is a keen chess player of a reasonable standard and he has played several chess programs under both windows and Linux. In expert mode, I think he wins two out of three games.  He still plays them so I think they must be a challenge to him but he isn't a chess master and I doubt the programs would be a challenge to such august people
Ian Jones,

It reminds me of the old story of the two most powerful computers in the world programmed to play each other at Chess.    
Computer 1 [White] d2-d4
Computer 2 [Black] After 1 nanosecond -  Resigns…
Richard Darnell, Tadcaster, North Yorkshire

EMMIGRANTS ON LINE

I have read that there is a site that lists the 20 million emigrants into the United States of America. Please can anybody come up with the address that my web search has failed to find?

Barry Hill, via email

Further to responses given to Barry Hills request, may I advise that the records included on the www.ellisislandrecords.org are not infallible.  Having searched both their web site on records on Ellis Island itself and not found what we were looking for, we had more success when in New York by visiting their National Archives & Records Administration.

 
Useful Internet sites for tracing people in USA are their White Pages phone book & Social Security Death Index plus Civilian Draft Registration Database all accessible through www.cindislist.com

Ewan Cappitt, Peterbough

SCHOOL DINNERS

I retired from teaching long ago - but still hear horror stories about the clerical time taken up with dinner money administration. Does anyone know of a simple, cheap (preferably free!), stand-alone program, which would help in a largish primary school?

Ray Glover, via email

Rodlan Administrative Software's School Lunch (Mac and Windows) accounts for all money and lunches eaten by students and adults. School Lunch replaces old ticket based programs with an easy to use computerised
system and can use bar coded lunch cards in conjunction with a bar code reader http://www.rodlan.com/
Jeff Ross, Stockport

SAILING LAPTOP

Later this year I will be off on a sailing adventure lasting approximately five months. The accommodation on board will be fairly rough and ready, with a damp salty atmosphere. Can anyone recommend a laptop or portable PC that will be able to endure this kind of hostile environment?

Janet Leslie, via email

Janet may want to try a Laptop by a company called Itronix, they have a machine called the GoBook Max which has been designed and fully tested to meet or exceed all military standards for ruggedization, including shock, drop, vibration, extreme operating temperature, water, condensing humidity, dust, and salt fog. Built and designed with the military and other demanding occupations in mind, the GoBook Max would be the perfect laptop to accompany Janet on her trip. For further information contact Itronix at www.itronix.com
Jubi Nawras,

CAN YOU HELP?

I have an interest in long-term weather prediction (for personal holiday planning), and used to appreciate the occasional view of the polar pressure chart on the BBC weather forecast.  I have searched high and low on the web
but can’t find a current polar chart.  Does anyone know of a site where it is available?
Doug Elliot, via email

Can anyone recommend an offline browser for reading newspapers? I merely want one that will work in the background – so that as I tick each story I am interesting in reading from the index – it will automatically start downloading. At the moment Internet Explorer demands that I await the full downloading of each story before proceeding to the next. An American company provided an excellent piece of software called Spoton that did precisely this but sadly no longer provide this service.

John Murphy, Bouniagues, France

Does anyone have formula or system, which ensures that 12 golfers playing 5 games of Fourball golf play with each other player approximately the same number of times? We have spent considerable time producing various formats by scrolling vertically and horizontally, but find that whilst we can achieve a perfect spread for one or two players, others play with one player 4 times and others not at all.

Roy Saunders, via email