. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 140 THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. [April, A PRACTICAL METHOD OF SETTING OUT A CIRCULAR RAILWAY CURVE, WITHOUT THE USE OF ANY INSTRUMENT FOR TAKING Let A be tlic commencement of a ciicuhir curve: perpendicular to the radius AO measure any distanct! AT, and from ii tlie middle of AT measure nm equal to An or »i T meeting Tm = .J T"- -^ y^ aT=~+2X0 = , then will m be a point in the curve. , measure in the direction of w m'to T' making- m T' = A
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 140 THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. [April, A PRACTICAL METHOD OF SETTING OUT A CIRCULAR RAILWAY CURVE, WITHOUT THE USE OF ANY INSTRUMENT FOR TAKING Let A be tlic commencement of a ciicuhir curve: perpendicular to the radius AO measure any distanct! AT, and from ii tlie middle of AT measure nm equal to An or »i T meeting Tm = .J T"- -^ y^ aT=~+2X0 = , then will m be a point in the curve. , measure in the direction of w m'to T' making- m T' = AT, and from T' the middle of mT measure /I'm'^ii'T', or n'm meeting Tm' = T»i, then will )»' be another point in the curve, and tlius any number of equidistant points may be found. Demonstration.âBecauseT)H X B T âA T-, and TB= = AT2+2AO', we have Tm = AT= -^ -j/AT'^ +2 A 6% then will m be a point in the curve. Again, join O HI and A01, then since T/>=:/( i.'i^n A, the point n is the centre of a circle passing through A, m, T ; therefore Am is perpendi- cular to T)», and nm a tangent to the curve at in. The method of proceeding on the concave side of the curve is equally easy, and depends on the same geome;rical principles. The foregoing supersedes the necessity of taking any angles. The methods given for laying out curves in the March and preceding " Railway Magazines," though founded on true principles, require either a theodolite or a table of sines and tangents, while this method requires neither, and appears simpler and more fitted for practice tlian any I have seen. HLSTORY OF PAPERHANGINGS. from a paper by Mr. , read before the Royal Institute of British Architects. (Continued from page 100.) In the former paper I endeavoured to trace the history of the art of paperstauiing up to the present time, and it is no\v my purpose to describe the manufacture, and give some account of the modern improvements that have been introduced. In
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