590 



SCIENCE 



[N. S. Vol. XLII. No. 1087 



arriyed at a final state of perfection, but it 

 is seldom that we find a critical description 

 of an instrument in our journals. Descrip- 

 tions there are from time to time, but these 

 are for the most part weak and insufficient. 

 Not only is a technical description re- 

 quired, which treats fully of both the optical 

 and mechanical details, but we need an ex- 

 tended series of observations with the in- 

 strument which have been made under the 

 ordinary conditions of practical work, and 

 these must be mathematically analyzed, and 

 the degree of the reliability of the results 

 clearly demonstrated. The description 

 should be equally thorough and complete, 

 including scale drawings showing the con- 

 struction of the instrument as well as 

 photographs of it. Nothing less than this 

 is of any use to the scientific cartographer. 

 While I am on the subject of instruments 

 I would draw attention to the importance 

 of the whole history of the development of 

 surveying instruments. In the latter part 

 of the eighteenth century Great Britain 

 provided the best class of surveying instru- 

 ments to all countries of Europe, at a time 

 when high-class geodetic work was being 

 commenced in several countries; and about 

 this time von Reichenbach spent a part of 

 his time in this country working in the 

 workshops of DoUond and learning this 

 particular class of work. Upon his return 

 to Bavaria he set up at Munich that estab- 

 lishment which soon provided instruments 

 of the highest class for many of the cadas- 

 tral surveys which were being undertaken 

 in Central Europe. At Munich there is 

 now a fine typical collection of such instru- 

 ments, but in this country the early ad- 

 vances of British instrument-makers of 

 surveying instruments are far from being 

 adequately represented in our National 

 Museum in a manner commensurate with 

 their importance. The keen and enlight- 

 ened zeal of geographers who are interested 



in this branch of the subject would doubt- 

 less quickly bring to light much still re- 

 maining that is of great interest, but which 

 is yet unrecognized, while a closer atten- 

 tion to instrumental equipment would lead 

 to improvements and advances in the types 

 that are now employed. There is no mod- 

 ern work in this country on the develop- 

 ment of such instruments, and reference* 

 to their history are conspicuously rare in 

 our journals, so that there is here an op- 

 portunity for those whose duties prevent 

 them from undertaking travel or explora- 

 tion of a more ambitious kind. In the same 

 way, those whose opportunities of field work 

 are few can find a promising field of study 

 in the early methods and practise of survey- 

 ing which have been discussed by many 

 authors from classical times onwards, and 

 for which a considerable amount of mate- 

 rial exists. 



In geodesy and surveying of high preci- 

 sion there is ample scope for all who are 

 attracted by the mathematical aspect of the 

 subject ; the critical discussion of the instru- 

 ments and methods employed and results 

 obtained, both in this country and in other 

 lands, provides opportunity for much work 

 of real value, while its bearing upon geol- 

 ogy, seismology, etc., has not yet been ade- 

 quately treated here. The detailed history 

 of this part of our subject is to be found 

 in papers which have been published in the 

 technical and scientific journals of other 

 countries for the most part; here too little 

 attention has been given to the subject, in 

 spite of the large amount of geodetic work 

 which has been executed in the British 

 Empire, and which remains to be done in 

 our colonies and over-seas dominions. 



The final expression of the surveyor's 

 detailed measurements is found in the map, 

 and the adequate representation of any 

 land surface on a map-sheet is both a sci- 

 ence and an art. Here we require addi- 



