THE ARCHIVE


This section is under development, but is intended to contain details of visits made by the society, items of historic interest, and details of talks of particular importance to the society.


GAIA and Sea Level


James Lovelock says in his new book "The Vanishing Face of Gaia" that the world population of six billion humans is too great - one billion would be appropriate, a figure that was reached two hundred years ago.  Nine billion are currently forecast for 2050.
The carbon footprint was  1 ton/year/person  in Victorian times, now it is 12 (USA 22).

 

Sea Level is now rising at 3mm per year, a rate that is expected to rise.  One metre may be seen by as the present generation of children grow up. Southern England is sinking 3mm a year, so the water level in London is rising at 6mm per year, about 1/4 inch.
Methane, a 20 times more potent greenhouse gas than CO2, is begining to escape from the Siberian continental shelf, with warmer Arctic waters.  The total amount of methane there and in the Siberian tundra is said to be equivalent to the word's coal reserves!   Beef cattle produce more methane than any other source of food.  




On 20th May 2005 Mr Matthew Blumler of the Quaggy Waterways Action Group gave the Society a talk on:     

The Restoration of the River Quaggy 

 The Quaggy Waterways Action Group had been set up as a charity in 1992, with the aim of using natural means to control its flow, instead of ever more concrete which still failed to prevent flooding.  Mr Blumler previously spoke to us about restoring the River Quaggy in 1996, when he made a strong case for such action, though the outlook for it was then bleak. 

He told us how the scheme has been implemented so far, what it has cost, and of the great environmental gains.  There was a brief discussion afterwards about its economic value: even without increased local property values the control of flooding would save future expense, which he told us was being monitored by DEFRA who are looking for a 40 year payback.


Visit to Sutcliffe Park 
   T

To complete the picture June Mackenzie wrote about the Visit which followed the talk:  nine members met up with members of the London Wildlife Trust for a tour of Sutcliffe Park on 23 June 2005 led by Antonia Scarr, a Conservation Officer of the Environment Agency. 

The policy of the Environment Agency is to allow plants to colonise the riverside in a natural fashion.  The high bank which would contain a severe flood was seeded as a wild flower meadow; and some riverside plants, which had been planted sparsely were spreading naturally.  The flat areas near the river, which were not seeded, are still largely bare.  Invasive weeds such as Himalayan Balsam were removed last year before seeding, and the same will be done this year.  We saw Dragon flies, Damsel flies, small fish in the river, and duck on the lake.    While we were there a group from ‘ Thames 21’ were engaged in removing litter from the river – though there was relatively little.  There had been a certain amount of vandalism when the park was first re-opened, but not much since. 
  
  
Professor Dave Elliott of the OU, at a talk to the Blackheath Scientific Society on 16-11-07 

  The proposed Severn Barrage is not considered the best way of harnessing Tidal Power.  Sea-bed machines around the coast could be connected to produce far more, continuous power at a lower cost per unit of energy.  They would not damage the environment as badly as a barrage.


  He brought copies of REWEW, the newsletter of the Network for Alternative Technology and Technology Assessment (NATTA) – which he edits.  NATTA can be accessed at:             http://eeru.open.ac.uk/natta/rol.html 
 
  
RARE EARTH ELEMEMTS 


Independent, 2-1-10

Rare Earth Elements are relatively abundant in the Earth’s crust, but the high cost of extraction means that only areas with rich deposits, in particular China, are worth exploiting.  The arrival of new technology means that global production has risen from less than 5000 tons in 1955 to the current level of about 120 000 tons per year.

Atomic   Name    (Symbol, Atomic      Use 
Number                            Weight) 


57         Lanthanum (La, 138.9)           Major ingredient for hybrid car batteries
58         Cerium (Ce, 140.2)                 Catalytic converters for Diesel engines
59         Praseodymium (Pr, 140.9)      Alloying agent for aircraft engines
60         Neodymium (Nd, 144.3)         Key element for high efficiency magnets & disc drives
61         Illinium (Il)                               not stated
62         Samarium (Sa, 150.4)             Lasers & nuclear reactor safety
63         Europium (Eu, 150.0)              Flat screen displays & lasers
64         Gadolinium (Gd, 157.3)           Shielding for nuclear reactors & compact discs
65         Terbium (Tb, 159.2)                 Low energy light bulbs
66         Dysprosium (Dy, 162.5)           Hybrid car motors
67         Holmium (Ho, 163.5)               Nuclear control rods & powerful magnets
68         Erbium (Er, 167.7)                   Fibre Optics
69         Thulium (Tm, 169.4)                Lasers & portable X-ray machines
70         Ytterbium (Yb, 173.5)              Earthquake monitoring equipment
71         Lutetium (Lu, 175.0)                Oil refining
Two more elements are considered Rare Earths as they tend to occur in the same ore deposits and have similar chemical properties:
21         Scandium (Sc, 45.0)                Aluminium alloys & high intensity discharge lamps
39         Yttrium (Y, 89.0)                       In: red TV phosphor; magnetic garnets; white LEDs; etc.
 
 
 
Navigation on a Troop Ship  by our late Member,  Bruce Mackenzie


In 1941 when I was a young soldier, I boarded a troop ship in Liverpool bound for an unknown destination.  I was interested to know our position, so I decided to improvise navigational instruments to track our voyage.  I had with me a prismatic compass, log & trigonometrical tables, a slide-rule, a pair of dividers and a school atlas.  The ship’s tannoy broadcast programmes from the BBC which gave me the date and Greenwich mean time.  I found that my compass was useless on deck due to the de-gausing system used to protect the ship from magnetic mines, however, it read fairly true down in the hold of the ship.

To determine longitude: 

I kept my watch running on GMT, corrected by BBC broadcasts, but the ships clocks were altered throughout the voyage.  The convoy did not appear to zigzag so I assumed that halfway between dawn and dusk was a good estimate of noon local time.  As the sun appears to travel 360º round the earth in 24 hours it will appear to travel 15º westward in one hour.  Thus by comparing noon at local time with Greenwich mean time an estimate can be made of the longitude of the ship.  
            

To determine latitude:

 
The elevation of the sun at noon is required in order to determine latitude.  To do this I improvised a sextant based on an empty cigar box.  I made an angle-scale, by interpolation from the angles of 30º, 45º, 60º and 90º obtained from equilateral and right angled triangles, which I fixed to the cigar box.  A small mirror was fixed to a moveable arm which could move over the degree scale, and two pins were used as sighting points.  One pin was placed as a sighting point at the pivot of the moveable arm and the other pin was placed at the beginning of the graduated scale (0 degrees).


In operation, the two pins are aligned with the horizon and the arm is moved to bring the image of the sun down to the horizon.  The angle of the arm is read from the degree scale and this angle is half the elevation of the sun.
The rate of change of the sun’s elevation at noon is not constant throughout the year but is fastest at the equinoxes and slowest at the solstices.  I assumed that the apparent motion of the sun follows a sinusoidal curve between the tropics, being over the equator at the equinoxes (21st March & 23rd Sept) and over the tropics at the solstices (21st June & 21st Dec).  These dates vary within a day or so depending on how close a leap year is.

 
By plotting such a curve the expected elevation of the sun at noon on any given date and latitude can be obtained.  Thus the measured elevation can indicate the latitude.


By using such makeshift instruments I was able to forecast correctly the day of our arrival at Cape Town!