45, CORNHILL, B.C., AND 122, REGENT STEEET, W., LONDON. 



The following extract from the Fourth Report of the Committee on Under- 

 ground Temperature, British Association for Advancement of Science, 1871, 

 will sufficiently prove the advantages of Negretti and Zambra's Patent 

 Maximum Thermometer without further comment : - 



" The Thermometer which the Committee have been employing for the last three years 

 is a Phillips's Maximum, having so fine a bore that the detached column of mercury which 

 serves as the index is sustained in the vertical position by capillary action, and will bear 

 a moderate amount of shaking without slipping down. Numerous instances, however, have 

 occurred in which the index has slipped in consequence of jerks or concussions sustained by 

 the thermometer in hauling it up from a depth. During the past six months the Secretary 

 has been in correspondence with Messrs. Negretti and Zambra respecting a proposed modifi- 

 cation of the Maximum Thermometer known by their name, which occurred to him more 

 than a year ago, and was described by him privately to some meteorological friends at the 

 last Meeting of the Association. It was then supposed to be new, but it now appears that 

 Messrs. Negretti and Zambra have made something of the kind for the last fifteen years. 

 Several changes, however, were necessary before the thermometer was adapted to the uses 

 of the Committee, and the first complete instruments were received in June last. They are 

 enclosed, like the thermometers previously used, in hermetically sealed tubes, for protection 

 against pressure, and they have the advantages (1) of Icing able to bear severe jolts without 

 derangement of their indications, and (2) of presenting to view a mucli broader column of 

 mercury, so as to be more easily read in a dim light. 



58. Mercurial Thermometer, with large Cup 

 shaped Bulb, (fig. 50), convex on the one side and concave 

 on the other, exposing a very large surface, suited for 

 experiment on Radiant or Accumulated heat. 



Price, Engine-divided on the Stem 150 



59. Negretti and Zambra's Patent Marine 

 Maximum Thermometer, (fig. 48.) As all other marine 

 thermometers are liable to give false indications from the 

 movements of the vessel in rough weather, this instrument 

 becomes a most important improvement. It is constructed and 

 used in a similar manner to No 57, the bulb of the thermometer 

 being uppermost; and no oscillation, however violent, can 

 disturb the indications. It is mounted in a strong wood or 

 metal frame, suitable for sea service. Price, 110 



60. Helio-Pyrometer. Mr. T. Southall, of Birmingham, 

 has published some very remarkable results obtained with 

 a Standard Maximum Registering Thermometer, having a 

 Blackened Bulb placed within a shallow box lined through- 

 out with black velvet, and having a soft cushion of the same 

 material in the bottom. Upon this cushion the Thermometer 



is to be placed, and covered over as closely as possible by a piece of plate 

 glass. Thus arranged, Accumulated Sun Temperatures have been noted by 



FIG. 50. 



