Spot heights show the height of a particular point on the map.Ĭontour lines are added to a map to show height and gradient. On a map, height is shown in metres above sea level. © Crown copyright and database rights 2015 Ordnance Survey Contours and spot heights Write the four figure northings number, but then add a third number to show how many tenths of the way up the grid square the place or object lies.Write the four figure eastings number, but then add a third number to show how many tenths of the way across the grid square the place or object lies.Six-figure grid references are found as follows: Six-figure grid references locate a place or object within a specific part of a grid square. The number will consist of another two digits giving a total of four, hence the name four figure grid reference. Then, write the northings number of the bottom left corner of the square (northings are found along the side of the map).First, write the eastings number of the bottom left corner of the square (eastings are found along the bottom of the map).Four-figure grid references are found as follows: The lines up the side of the map are called northings as they travel towards the north.įour-figure grid references locate a place or object within a grid square. The lines across the bottom of the map are called eastings as they travel towards the east. Every OS map has a grid, which is shown using faint blue lines. Grid references accurately locate places on a map. This may be used to show larger areas or regions. This may be used for individual towns and cities. Scale is shown as a ratio, eg 1:25,000 means that 1 cm on a map represents 25,000 cm or 250 m in real life. The relationship between the features on the map to the real size on the ground is called the scale. Maps show objects as being much smaller than they are in real life. Each OS map has a key to show what the symbols mean. OS maps show physical and human features as symbols. This tooth has the longest root, which makes the maxillary canine the longest tooth.How to use an OS map, using scale and grid references Using a key The incisal surface of the maxillary canine contains rounded mesioincisal and distoincisal angles. The mesial surface of a maxillary canine is relatively flat compared to the distal surface, which is more rounded. The mesial surface tapers from the height of the contour to the neck part of the tooth. The height of the contour of the maxillary canine is as follows: However, it is not as prominent as in the incisor teeth. The cingulum is very developed in canine teeth, and it makes these teeth wider buccolingually than mesiodistally. The lingual ridge extends from the cusp apex towards the cingulum, and it divides the lingual fossa into two smaller fossae - mesial and distal lingual fossae. The palatal surface shows such structures as the cingulum, mesial and distal marginal ridges and lingual ridge. Also, the maxillary canine has a very noticeable notch at the cementoenamel junction. These lobes are separated by the mesial and distal developmental grooves. The central lobe is better developed than the mesial and distal. The labial surface contains three lobes - mes ial, central and distal. The mesial height of the contour is closer to the cusp. The length difference between both cusp ridges is present because of the difference in the height of the contour on the mesial and distal surfaces. The mesial cusp ridge is shorter than the distal cusp ridge. The maxillary canine does not contain an incisal ridge, but it has a cusp ridge composed of the mesial cusp ridge and distal cusp ridge. The top of the cusp is known as its apex - cusp apex - and it is centered to the long axis of the tooth. The maxillary canine presents with only one cusp on its incisal surface.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |