GEOGRAPHICAL LATITUDE. 785 



iites of arc inhislatitudeof Paris, and Bauerufeind' calls it •'eiuen vol- 

 lig werthloseu Versiich die Grosse der Erde zu messen.'' Fate was 

 kinder to Fernel than his critics, and be cannot be deprived of the 

 uniqne honor of having first given to the world the nearly exact length 

 of a degree of latitude.- 



Almost a century later (1615) Willibrord Snellius, a famous Dutch 

 physicist, made his celebrated trigonometrical survey of a line between 

 Bergen op- Zoom, Leyden, and Alkmaar, which line, according to his 

 calculation, has a length of 34,018.20 perches of the Rhine. The dis- 

 tance in latitude he determined at 1° lU' ; and this, compared with the 

 distance surveyed, gives a mean value of the degree of latitude of 28,- 

 500 i)erches=55,100 toises of Paris.^ The result was, according to more 

 recent calculations, 2,000 toises too short, an error of nearly 3^ per 

 cent.* He himself was persuaded that the result was not accurate and 

 therefore undertook a second survey in 1622, but was prevented by 

 sickness and death from completing it with the necessary calculations.* 

 The base line was only 326.43 perches long (=631 toises and about 1 

 foot), an extremely short scale, considering the imperfection of his in- 

 struments and the fact that his triangles contained very many acute 

 angles. 



The first English survey of a degree of latitude was made by a 

 sailor, liichard Norwood, who determined astronomically the latitude 

 of London and York, then measured with a chain the intervening dis- 

 tance, allowing in his calculations for the unevenness of the laud, the 

 windings of the way, and also for refraction, declination, and parallax. 

 He found the difference in latitude to be 2° 28,' instead of 2° 25'. His 

 measurement gave 367,176 feet for the degree of latitude, which, allow- 

 ing 2.1315 English yards to the toise, gives 57,420 toises as the value of 

 a degree.^ He had been led to make the survey from the practical 

 need of information as a mariner, and published the results thereof in 

 1637 in a work entitled "The Seaman's Practices."' 



About the middle of the seventeenth century (1645) Father Riccioli, 

 an Italian Jesuit, ran a series of triangles in the neighborhood of 

 Bologna, measured a base of 1,094 paces 2^ feet, and by observations of 

 a number of stars for determining the distance in latitude between the 

 end points of his line, arrived at very different results, so that taking 



' Bedeutung, etc., 39 n. 22. 



2 Lalande, M^m. de I'Acad. Roy., 1787, p. 222; Jordan, Vermessuugskunde, ii, 4. 



^■Cassini, Grandeur, etc., 304. 



' Pescbel, Erdkunde, 39(). Bauernfeind (as above, p. 39, n. 20) says i of the error 

 was in the geodetic work, ^ in the astronomical observations. 



* Bauernfeind, 15, 1(5. 



'Pescbel, Erdkunde, 395, n., quotes Maapertuis, Figure de la terre, p. viii, as giv- 

 ing as the result of tbis survey 367,196 feet— .57,300 toises for the degree of latitude, 

 an evident arithmetical error in reducing to toises, even if the number of feet given 

 veere correct. 



'The writer adopts the account given in the Encyc. Brit., art "Navigation," and 

 Jordan, Vermessungskunde, ii, p. 78, for the value of the toise. 

 H. Mis. 224 50 



