126 Mr Rogers on the Construction of Achromatic Telescopes. 



about nineteen or twenty catties, and sells at Matan for about 

 three dollars. It is collected by the Daya, and is of superior 

 quality, as tools made of it are not steeled, and is in great de- 

 mand among the natives. It is imported advantageously at 

 Pontianak both from Matan and frorii Banjermassin, at which 

 place it is known by the name of Bissi Desa, or Country Iron. 



The animal productions which add to the exports of this Re- 

 sidency are wax, bezoar stones, and deer horns, but very little 

 birds nest is found. The wax is of good quality when collected 

 by the Daya, who find the hives most commonly on the Katapan 

 tree, but, passing through many hands before it is exported, it 

 is then generally adulterated. The bezoar stones, or Batu Ga- 

 liga, the Daya allege, are collected by them from the muscular 

 parts of animals, particularly the porcupine (Landak,) and the 

 various species of Simia ; and they conceive that they are pro- 

 duced by wounds received from other animals, especially the 

 wild hog and Simia. On the coast this account appears to be 

 believed, although contrary to the received opinion that the be- 

 zoar is produced in the stomachs of certain ruminating animals. 



No meteorological journal has been kept, * but to judge from 

 personal feeling, the climate must be very warm ; the dense 

 forests and extensive marshes would warrant the inference that 

 the Residency is unhealthy, but it is considered otherwise, with 

 the exception of the diamond district. The prevalent diseases are 

 diarrhoea, dysentery, remittent and intermittent fevers, drop- 

 sical, rheumatic, and bilious complaints, small-pox, and the lues 

 venerea. While the cholera morbus raged it made dreadful ra- 

 vages. Once at Pontianak the whole garrison were attacked, 

 and the Resident, who fortunately escaped, was the only per- 

 son to administer the usual remedies. 



Art. XXII. — On the Construction of large Achromatic 

 Telescopes. By A. Rogers, Esq.-f- 



In this paper the author describes a new construction of an 



• We anxiously hope that a meteorological journal will be established at 

 this residency. Its proximity to the equator would render the observations 

 of great importance. — En. 



T Mr Rogers's paper was read before the Astronomical Society on the 1 1th 

 of April. 



