AMERICAN INSTITUTE. 201 



ther lessens the liability to any inaccuracies which might occur. 

 He also exhibited one of his improved adjusting tripods, which 

 unlike those in general use, allows the theodolite, transit, level, 

 &c., if not set over the line, to move from one to three inches in 

 any direction without moving the legs of the tripod, thereby 

 saving much time in setting the instrument. 



The judges to whom these articles were referred, report that, 

 these surveying instruments are considered the best of their kind 

 exhibited — strong, solid, susceptible of easy adjustment in many 

 ways, and well calculated for service. [./5 silver medal awarded. 



Insulated Telegraph Wire. 

 Samuel C. Bishop, 181 Broadway, New-York. 



This article being a gutta-percha insulated wire, protected by 

 lead covering, is the most novel that has come under our obser- 

 vation. The manulacture of it would at first seem an impossi- 

 bility. We liave examined the machinery used to produce it, the 

 two patents issued to the inventor, and various samples of its 

 production. Molten lead is made to envelope gutta-percha wire, 

 by hydraulic pressure, yet without destroying the valuable prop- 

 erties of the gum. This is effected by an arrangement which 

 interposes a flowing stream of cold water between the lead and 

 the gutta-percha, except at the moment of contact. By recent 

 analyses in England, gutta-percha is found upon exposure to air 

 to be converted into two substances of different chemical consti- 

 tution, entirely different from the pure gum, being non-insulating 

 and also brittle or rotten ; hence it has been discarded to a great 

 extent in this country as an insulator to wire, unless protected 

 from air. The English subterranean telegraphs, of gutta-percha 

 covered wire, buried in wooden boxes, have been repeatedly 

 destroyed by decay, while submarine wires kept from air have 

 remained sound. The lead covering is air tight, and ten miles of 

 the fabric can be made in a continuous length. 



MISCELLANEOUS. 



Reifercheid's Compound Solvent. 

 H. Reifercheid, 289 Broadway, New- York. 



Report on Reiferscheid's compound solvent, for dissolving the 

 incrustations found in steam boilers : 



The undersigned judges, appointed to examine and report upon 

 the effects of Prof. Reiferscheid's patent compound solvent, upon 



