232 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



third, the pressure, temperature, and altitude. The advan- 

 tages which the new tables of Kiefer possess over the older 

 ones of Biot are, first, all interpolations are avoided, and 

 there is left for the computer only the simplest operations, 

 viz., addition and subtraction, which can even be executed 

 upon the abacus that is so widely used in Russia. Second, 

 the terms depending upon the temperature of the air and 

 the altitude are separated from those that are independent 

 of these arguments ; so that we see directly the influence of 

 tliese .upon the result. Third, notwithstanding that the ex- 

 tent of the new tables does not exceed 114 small pages, yet 

 is the range so extended as to cover any altitude that can 

 joossibly occur even in the Caucasus. Kiefer's tables do not 

 take account of the moisture in the atmosphere, because, as 

 he says, the computations that introduce that argument 

 Q^ive results differino; from the sjeodetic determinations more 

 than if moisture is omitted. Biofs Tafdn^ computed by 

 Kiefer, Tiflis, 1874. 



NEW^ FORM OF MERCURIAL HORIZON. 



Those who have had frequent occasion to observe the heav- 

 enly bodies as reflected from a bath of mercur}^ will welcome 

 the announcement that it is possible to construct such a bath 

 in a manner to diminish, if not entirely obviate, the very an- 

 noying vibrations to which the mercury is subject even when 

 the origin of the vibration is unknown. Such a. bath of mer- 

 cury, established upon a pier of its own, entirely isolated from 

 the building, has been known to tremble under the influence 

 of vibrations communicated from railroad trains, or the blast- 

 ins: of rocks, from two to five miles distant. In the neinjh- 

 borhood of a large city the surfiice is never quiet by day or 

 night. In order to obviate this annoyance, it is well known 

 that Professor Airy, of Greenwich, suspended the basin con- 

 taining the mercury from the fourth of a set of four frames, 

 each of which was suspended from the other by threads of 

 India rubber. By this means the mercury was relieved from 

 the influence of the minute vibrations to which the ground 

 near London is continually subject. Mr. Lane, of the Coast 

 Survey, however, announces that if in the bottom of the basin, 

 near its edge, we cut a circular trough, such that the greater 

 mass of the mercury may run into it, we may leave over the 



