On the Use of the Pocket Box-Sextant. 51 



them : and it can now confidently be affirmed, that a careful ap- 

 plication of apparently slender means, will produce very close 

 approximations, and highly valuable when made in places where it 

 is very unlikely that men of great scientific acquirements, accompa- 

 nied by costly instruments, may ever arrive. Many a military man 

 and traveller may unexpectedly find themselves in the course of their 

 journeys near ruins where no one has travelled before, or at least 

 no record appears to that effect : this has happened to those who 

 have come overland from India to Europe : or, they may reach a 

 place well described by others, but who have not given its geogra- 

 phical situation ; but which is. in many cases, so easily obtained, that 

 we can only attribute the omission to some cause like that before 

 suggested. Now it is hoped that the following experiments, care- 

 fully made for the purpose, will arrest the attention of those who 

 seek information and knowledge in foreign countries. It would 

 be of use if they would merely register the observations they may 

 make, and leave the calculation of them to other persons on their 

 return ; in that case all that is required is a faithful register, dis- 

 tinctly kept, of such observations, with temperature, and such 

 various particulars as may be collected, according to the instruments 

 possessed by the person. 



The amusement a small set of instruments will often afford to 

 a person in a foreign country is considerable : his determinations 

 will be satisfactory to himself, they will corroborate or disprove 

 those of others, and leave less to mere guess than is too often the 

 case. How many various accounts have we seen of the breadth 

 of the Hellespont, and with how little trouble might the matter be 

 settled, by measuring or pacing a base, and taking- a kw angles 

 with the instrument shortly to be mentioned. How many different 

 heights have been assigned to the Pillar, of Pompey, or the 

 Pyramids of Egypt, and many other similar objects, and yet the 

 point could be settled in half an hour at most, by using an instru- 

 ment so small and light, that whoever visits such places, or enters 

 a magnificent temple or other building, should never be without 

 it ; as he may assure himself of the height of its columns, 8(c., in 

 a few minutes, within a few inches of the truth, and with scarcely 



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