Can your sundial really tell the time?

Written by Hugh Harris-Evans

"I am a sundial, and I make a botch Of what is done far better by a watch"

So wrote Hilaire Belloc, but is this really fair? Sundials arerepparttar earliest known form of time-keeping having been used for some five thousand years. The Greek historian Herodotus stated that sundials were first used byrepparttar 113431 Chaldeans and Sumerians in Babylonia which was part ofrepparttar 113432 modern Iraq. They used vertical rods on their buildings and notedrepparttar 113433 position ofrepparttar 113434 shadow to recordrepparttar 113435 passing ofrepparttar 113436 hours. The concept was developed byrepparttar 113437 Greeks and Romans who constructed various different shapes of dial to enable them to tellrepparttar 113438 time andrepparttar 113439 season ofrepparttar 113440 year. Usually these were bowl-shaped dials with vertical or horizontal gnomons (shadow-casters) and hour lines marked inrepparttar 113441 hollow ofrepparttar 113442 bowl. Overrepparttar 113443 years more elaborate designs were produced untilrepparttar 113444 advent of accurate clocks whenrepparttar 113445 function ofrepparttar 113446 sundial became more decorative than as a reliable means of tellingrepparttar 113447 time.

The question is often asked "Can a sundial really tellrepparttar 113448 correct time?" to which you will receiverepparttar 113449 Alice in Wonderland reply that it depends upon what you mean by "the correct time". Our clocks and watches work onrepparttar 113450 basis of there being exactly twenty-four hours between one day andrepparttar 113451 next but, because ofrepparttar 113452 eliptical nature ofrepparttar 113453 earth's orbit aroundrepparttar 113454 sun,repparttar 113455 time shown onrepparttar 113456 sundial will vary according torepparttar 113457 seasons. In February byrepparttar 113458 clockrepparttar 113459 sun is almost fifteen minutes slow, whereas duringrepparttar 113460 spring and summer months it gains and loses between four and six minutes in two cycles. Atrepparttar 113461 other extreme in Novemberrepparttar 113462 sundial appears to be some seventeen minutes fast. In factrepparttar 113463 sundial is accurate on only four days ofrepparttar 113464 year, about April 15, June 14, September 2 and December 25. Some sundials include a table showingrepparttar 113465 deviation from "clock time" according torepparttar 113466 date.

The time indicated byrepparttar 113467 sun will also vary withrepparttar 113468 location ofrepparttar 113469 dial. The sun travels acrossrepparttar 113470 sky atrepparttar 113471 rate of fifteen degrees per hour so every degree of longditude represents a difference of four minutes fromrepparttar 113472 standard meridian forrepparttar 113473 region. The angle ofrepparttar 113474 gnomon also depends onrepparttar 113475 situation, so to set up your sundial correctly you need to know bothrepparttar 113476 latitude and longditude of its location. Forrepparttar 113477 United States andrepparttar 113478 United Kingdom this site can providerepparttar 113479 information. The gnomon should be set atrepparttar 113480 angle in degrees which is equal torepparttar 113481 latitude of your location. The sundial can then be fixed withrepparttar 113482 gnomon pointing torepparttar 113483 Pole Star. There are various ways of achieving this,repparttar 113484 easiest of which, is to use a compass adjusted forrepparttar 113485 magnetic variation. Further details are beyondrepparttar 113486 scope of this article, but for those interested look at this site. If you have read this far you will have discovered that there is a great deal more torepparttar 113487 sundial than a mere item of garden decoration. If this has piqued your interest inrepparttar 113488 subject, then you are not alone. There are Sundial Societies in countries aroundrepparttar 113489 world. The North American Sundial Society has details of its objects and activities on its website.

Starting Vegetable Garden Seeds & Plants Indoors

Written by David Selman,

Starting Plants IndoorsSeeds can be germinated and seedlings started in a box, pan or flowerpot of soil in a window. In addition to having at least 6 hours of direct sunlight each day,repparttar room must be kept reasonably warm at all times.

Washed fine sand and shredded sphagnum moss are excellent media in which to start seeds. Place a layer of easily drained soil inrepparttar 113430 bottom of a flat and cover this soil with a layer - about three-fourths inch thick - of either fine sand or sphagnum moss. Pressrepparttar 113431 sand or moss to form a smooth, firm seedbed.

Then, using a jig, make furrows inrepparttar 113432 seedbed one-half inch deep. Waterrepparttar 113433 sand or moss thoroughly and allow it to drain.

Sow seeds thinly inrepparttar 113434 rows and coverrepparttar 113435 seeds lightly with a second layer of sand or moss. Sprinklerepparttar 113436 flat, preferably with a fine mist, and coverrepparttar 113437 flat with a sheet of clear plastic film. The plastic film diffuses and subduesrepparttar 113438 light and holds moisture inrepparttar 113439 soil and air surroundingrepparttar 113440 seeds. Plastic films offer advantages over glass coverings in that they are light in weight and are nonshattering. Placerepparttar 113441 seeded and covered flat in a location that is reasonably warm at all times and has 6 hours of direct sunlight each day. The flat will require no further attention until afterrepparttar 113442 seedlings have developed their first true leaves. They are then ready to transplant to other containers.

It is seldom possible to keeprepparttar 113443 transplanted plants in house windows without their becoming spindling and weak. For healthy growth, place them in a hotbed, coldframe, or other place where they will receive an abundance of sunshine, ample ventilation, and a suitable temperature.

Strong, vigorous seedlings can be started under 40-watt fluorescent tubes. These tubes should be 6 to 8 inches aboverepparttar 113444 seedlings. Temperatures should be about 60F at night and 70F duringrepparttar 113445 day. Best results are obtained ifrepparttar 113446 fluorescent fixture is next to a window to increaserepparttar 113447 amount of light reachingrepparttar 113448 young plants. Soil pellets arerepparttar 113449 simplest and easiest method for starting plants and are readily available from garden supply stores and other sources. Soil pellets are a well-balanced synthetic soil mixture and are free of soilborne diseases and weeds.

Special Devices for Starting Plants In determiningrepparttar 113450 type of equipment for starting early plants,repparttar 113451 gardener must considerrepparttar 113452 temperature and other climatic conditions in his locality, as well asrepparttar 113453 nature ofrepparttar 113454 plants to be started. Hardy plants, such as cabbage, need only simple inexpensive facilities, but such heat-loving, tender seedlings as peppers and eggplant must have more elaborate facilities for successful production. Inrepparttar 113455 warmer parts ofrepparttar 113456 United States, and inrepparttar 113457 well-protected locations elsewhere, a coldframe or a sash-covered pit onrepparttar 113458 sunny side of a building usually suffices. In colder sections, or in exposed areas elsewhere, some form of artificial heat is essential. Where only a little protection against cold damage is needed, a coldframe in which a temporary bank of lamps can be placed may be sufficient. The hotbed, lean-to, or sash greenhouse heated by manure, pipes, flues, or electricity are all widely used,repparttar 113459 choice depending on conditions. A comparatively small plant-growing structure will provide enough plants for several gardens, and joint efforts by a number of gardeners will usually reducerepparttar 113460 labor of producing plants. The plant-growing structure should always be on well-drained land free from danger of flooding. A sunny, southern exposure on a moderate slope, with trees, a hedge, a board fence, or other form of windbreak onrepparttar 113461 north and west, makes a desirable site. Plenty of sunshine is necessary. Hotbeds and other plant-growing devices require close attention. They must be ventilated at frequent intervals, andrepparttar 113462 plants may require watering more than once daily. Convenience in handlingrepparttar 113463 work is important. Sudden storms may necessitate closingrepparttar 113464 structure within a matter of minutes. Plant growing at home should not be undertaken by persons obliged to be away for extended periods, leavingrepparttar 113465 plant structure unattended. A tight well-glazed structure is necessary whererepparttar 113466 climate is severe; less expensive facilities are satisfactory elsewhere. Covers for hotbeds and coldframes may be glass sash, fiber glass, plastic film, muslin, or light canvas. Inrepparttar 113467 moderate and cooler sections ofrepparttar 113468 country, standard 3- by 6-foot hotbed sash is most satisfactory. Even this requires supplementary covering with canvas, blankets, mats, or similar material during freezing weather. The amount of covering is determined byrepparttar 113469 degree of heat suppliedrepparttar 113470 structure,repparttar 113471 severity ofrepparttar 113472 weather, andrepparttar 113473 kind of plants and their stage of development. Farther South, where less protection is necessary, a muslin cover may be all that is needed and for only a part ofrepparttar 113474 time.

Many substitutes for glass as coverings for hotbeds and coldframes are onrepparttar 113475 market. The most widely used substitutes are various kinds of clear plastic film. Some of these have a lifespan of only one season, and others a lifespan of 3 to 5 years. Clear plastic film transmits as much light as glass inrepparttar 113476 visible range, and more than glass inrepparttar 113477 ultraviolet and infrared ranges.

The film comes as flat sheets (on rolls) and in tubular form. Flat-sheet film is used for tacking onto wooden frames;repparttar 113478 tubular form is used for enclosing metal tubular frames with a tight double layer of film. Large plant hoods made from semicircular aluminum or galvanized steel pipe and fitted with a sleeve of tubular plastic film make excellent coldframes or seasonal row covers. When used in this way, a double layer of plastic film provides an air space that insulates against 4 degrees to 7 degrees of frost temperature change. Electrically heated plant beds are ideal forrepparttar 113479 home gardener, provided electric rates are not too high. The beds may be built any size. Because they are equipped with thermostatic control, they require a minimum of attention. It is not possible to buy frames - completely equipped with heating cables, switches, and thermostats - ready to assemble and set in position. Fillrepparttar 113480 frames with soil or plant boxes and connect to a source of current. Small frames may be removed atrepparttar 113481 end ofrepparttar 113482 season and stored; larger frames are usually treated as a permanent installation. For more detailed information, see USDA Leaflet 445, Electric Heating of Hotbeds.

Cont'd on page 2 ==> © 2005
Terms of Use