Selected quad for the lemma: end_n

Word A	Word B	Word C	Word D	Occurrence	Frequency Band	MI	MI Band	Prominent
end_n	east_n	point_n	west_n	1,970	5	9.4719	5	true

Text snippets containing the quad

ID	Title	Author	Corrected Date of Publication (TCP Date of Publication)	STC	Words	Pages
A44313	Animadversions on the first part of the Machina coelestis of the honourable, learned, and deservedly famous astronomer Johannes Hevelius, consul of Dantzick together with an explication of some instruments / made by Robert Hooke ...	Hooke, Robert, 1635-1703.	1674 (1674)	Wing H2611; ESTC R38964	66,602	94

your Eye-Glass and observe how far the cross Threads are now removed from it either Northwards or Southwards upwards or downwards then as near as you can by your judgement half that Difference and by the Screws move the Frames that the Threads may stand in the middle between the two Points then take notice again of the Points shewn by the Threads and turn the Tube again Do this so many times till you find upon converting the Tubes that you see the same Points to be marked by the Crosses of the Thread-Sights with which end soever you look on them and then the Tube will be exact and fit for use The reason of this adjusting will be sufficiently plain to any one that shall consider the 14th Figure Where let v represent the middle of the Tube tub or the place of the Eye and let w represent the Object seen Westwards and e the Object Eastwards at the first view then keeping the middle of the Tube exactly upon the same Point u turn the end of the Tube t towards the East and the end b towards the West and find out first the Eastern Object e and finding the other Cross to direct now to the Point p and not to w divide the Distance between the Point w and the Point p as exactly as you can in half which if you chance to hit exactly at first it will be the middle Point m but if you do not but you rectifie it only to r then by the next turning of your Tube you will find s where you must again rectifie to half the Difference between s and r now the Difference being grown yet less you will a 3d. or 4th time set it so exactly as to see the Points m and e which lye in the straight Line with the Center of the double Tube The 4th thing wherein this Quadrant exceeds the Common is for its accurateness for taking Altitudes and this is done by the help of a Water-Level for adjusting the exact Perpendicularity thereof This Level may be made and fixed so exactly that any Observator may be sure of the Level of his Instrument to a Second or two The Level it self is nothing but a short Tube of Glass about 6 or 8 inches long Hermetically sealed at each end and filled with a Liquor that will not freeze nor grow foul with standing The Glass as near as can be gotten should be Cylindrical and straight it being the better the nearer it be to a straight provided it have a sensible bending or swelling in the middle the gibbous part of which should be set upwards and a proper Cell and Box made for it of Brass This Glass is to be filled almost full of distill'd Water to which about a 3d. part of good Aqua-fortis or spirit of Niter hath been put to keep the same from freezing and also from growing foul then carefully sealed up Hermetically and placed in its Box of Brass and with hard Cement fixed into the same which by Screws is fixed to that side of the Quadrant that is to lye Horizontal The Brass Box being thus fixed to the right side of the long fixt Tube ap ap ap and underneath the Quadrant so as not to hinder the free movement of the arm c c c as at x x the next thing to be done is by it to set the Quadrant truly Horizontal which is thus performed Setting the side a p a p a p Horizontal and the Limb of the Quadrant upwards and looking in at the Center take notice of two Objects in the Horizon opposite to each other observe the limits of the bubble of Air on the top of the Liquor on each side of the middle of the Level and make a mark then turning the ends of the Quadrant set it till the ends of the bubble stand as in the former Observation then look again at those Objects in the Horizon and find what the difference is between these opposite Objects and those in the former Observation then halve the difference between them as near as you can and by your eye set the Sights to the middle between them by inclining the Quadrant then by the Screw that rectifies the Level set the Glass-Level so that the ends of the bubble may be equally distant from the middle and convert the Quadrant again and see if the ends of the bubble standing at the same marks the two opposite Telescope-Sights do see the same Objects for if so you are assured of the perfect Horizontality of the Sights upon the fixt arm of a p a p but if you do not find it to direct to the same Objects continue examining and converting till you find it perfect Now this way of Perpendicular being subject to the inconvenience of heat and cold which doth rarifie and condense the Liquor and consequently make the bubble of Air less or more care must be taken to mark all the varieties of those kinds of the bubble that are caused by the degrees of heat and cold which you may thus easily effect Reduce the Liquor in the Tube of the 24th Figure by the help of Ice and Salt to as great a degree of cold as you can then by the method newly directed set the Quadrant Horizontal and mark the two ends of the bubble with 44 then by gently applying heat to the ambient Air warm likewise the Water and observe the expansion thereof at both its ends and mark them on the Glass with the point of a Diamant as 33. 22. 11. 00. which being done it will be exceeding easie at any time to adjust the Quadrant to any accurateness desired by being careful to see that the two ends of the bubble be proportionably extended as to 00 11 22. 33. 44 c. or to any intermediate space The Contrivance of fastening and adjusting this Level to the Quadrant or other Instrument will be very easily understood by the Delineation thereof in the 24th Figure Let a a a a represent the Frame or Plate of Brass which by four Screws d d d d is fixed to the Tube as before This Plate hath 4 upright Cheeks b b c c between which the Brass Box e e e e into which the Cylindrical Glass-Level f f is fixed with hard Cement is held steady without any manner of shaking This Brass Box at the end of it near the right hand hath a Pevots which are fitted exactly into 2 small holes in the Cheeks c c and at the other end next the left hand hath a small Screw-Pin g which holds it down fast to the bottom Plate and keeps it from rising out from between the Cheeks b b which a very strong Spring lying underneath it between the Plate a a and the Box e e would otherwise force it to do By this Screw the Level is to be adjusted to the Sights of the Quadrant by the way I just now described and being once thus adjusted and fixed 't is not easily put out of order without moving or