NATURE 



337 



THURSDAY, AUGUST 23, 1877 



MAURITIUS OBSERVATORY 

 Reports for 1874 and 1875 0/ the Observatory, Mauritius 



{Appendices to Minutes of Council No. g 0/ iSy^t '^"'^ 



No. 24. of 1876). Mauritius Meteorological Results, 



1874 and 1875. 

 '"P'HESE Reports give an interesting account of the 

 J- progress of the Royal Alfred Observatory at Mau- 

 ritius. The first division is devoted to the " Buildings, 

 Grounds, and Water Supply ; " this is a more important 

 division than may be supposed at first sight. It appears 

 in the Report for 1S74, that in an attempt to arrange the 

 grounds extensive pits were formed which were con- 

 verted, through heavy rains, into noxious pools ; while in 

 next year's Report it is mentioned, under the head 

 " Staff," that all had acted with " great zeal and per- 

 severance notwithstanding occasional attacks of fever 

 from which no one here has been exempt." The cause is 

 indicated to be in a neighbouring marsh left undrained 

 since 1872 or 1873. 



In a similar report by the director of an observatory 

 in South India to the Government, the construction of a 

 road from the Observatory near the sea to another on the 

 summit of the Ghats is mentioned as having been placed 

 under his superintendence. The surveyor, however, who 

 had to see the trace cut out, was unable to induce the 

 coolies to accompany him through a certain part of the 

 country, as a tiger had there carried away different 

 members of a hill tribe. The director requested the 

 Government to offer a suitable reward for the death of 

 the man-eater, but in vain ; the only reward promised 

 being that usually given, the estimated value of the skin 

 The worth of the thing was what it would bring. A 

 cooly, unlike a soldier, costs nothing to make him a 

 useful machine ; if a few coolies are snapped up by a 

 hungry tiger others can always be had equally capable at 

 the same daily rate of hire ; the finances of the State do 

 not suffer. If the director of the Observatory, the sur- 

 veyor, or any other salaried officer, should be eaten, that 

 would be a positive gain to the "Treasury, since the pen- 

 sion due for previous services would be at once cancelled. 

 No one can estimate the financial loss if a healthy officer 

 should escape in such a case ! 



No Government, of course, would reason in this way, 

 and we feel sure that of Mauritius will do what they can 

 to make the scientific work they have so well begun as 

 little dangerous as possible. 



There remains, however, an annual source of discomfort 

 and mischief in countries like the Mauritius where the 

 rainfall is heavy — the '' leaking" of the roofs. This is a 

 more serious matter, financially speaking, than the health 

 of the staff, since the whole objects of the observatory 

 may be defeated by the action of humidity on the 

 different instruments, including the object-glasses of the 

 photo-heliograph, the equatorial, and other telescopes. 

 In the Report for 1S75 it is remarked that "the roof of 

 the main building, which leaked considerably, has been 

 repaired on two occasions. It still leaks, however, though 

 not nearly as much as it did in February last, when some 

 of the rooms were flooded, and books and papers were 

 more or less damaged," &c. The roof of the Magnetic 

 Vol. XVI. — No. 40S 



Observatory is also noted as " now almost water-tight." 

 We hope the importance of this matter will be thoroughly 

 appreciated by the Government, since the preservation of 

 the instruments and the whole value of the results to be 

 obtained from them depends upon it. 



The magnetical instruments have been placed twelve 

 feet under ground. We are afraid that this is not a good 

 arrangement. Dr. Lament tried a similar plan at Munich 

 during five years, and the damp rotted the wooden 

 supports of the roof, &c. He was at last obliged to place 

 all the instruments above ground. We have also tried a 

 similar method for a short period ; but the humidity in 

 such positions, and especially where the soil is frequently 

 saturated with water, is destructive of all satisfactory 

 results. The great object sought is constancy of tempera- 

 ture, and this can be gained to a great extent by 

 placing the instruments within an inner room with thick 

 ceiling and inner walls. Such a room need be entered 

 rarely, and with self-registering apparatus the parts 

 requiring manipulation may be placed in an external 

 chamber communicating with the instrument room by a 

 small opening in the wall. 



Dr. Meldrum, the able and zealous director of the 

 observatory, has both magnetical and meteorological self- 

 registering apparatus, and in connection with the latter 

 he receives meteorological observations from various 

 stations. Astronomical work is limited chiefly to certain 

 occasional phenomena (the transit of Venus was observed). 

 There is a time-ball ; a tide-gauge is expected ; sun- 

 spot pictures are taken with the photo-heliograph ; sea 

 observations from ship-logs are studied ; storm-warnings 

 are given ; a magnetic survey has been begun, and special 

 researches are undertaken. 



Among the latter are useful practical studies connected 

 with cyclones, which merit the greatest encouragement. 

 Dr. Meldrum has noticed in his Report for 1875 the 

 difference of his and M. Faye's views as to cyclonic 

 movements. The latter insists that the wind moves in 

 circles round the centre, while the former upholds spirally 

 inward flowing currents (see Nature, vol. xii. p. 45S). 

 This difference involves a most important question. 

 According to the usual rule, as M. Faye says, the centre 

 of the cyclone is at right angles to the direction of the 

 wind ; according to the other the wind is blowing towards 

 the centre. That is an exaggeration of Dr. Meldrum's 

 view ; but in the Report for 1875 he says (Art. 90) that if 

 a ship runs before the wind to north-west, believing the 

 centre of the cyclone to be to north-east, the latter may 

 really be to north or to north by west ; that is to say, may 

 make an angle of 45° or even of only 34° with the wind 

 direction. We cannot accept Mr. Meldrum's theory of 

 spiral cyclonic movements with the associated ascending 

 currents, in which we have never seen any reason to 

 believe ; but we think there is considerable evidence for 

 affirming that the angle made by the direction of the 

 surface wind and that of the cyclone centre is generally 

 less than 90° ; and we do not think that M. Faye, in his 

 effort to apply mechanical principles to the movements of 

 the aerial masses, has had all the conditions of the problem 

 before him, a fact which will appear more evident when 

 the results we have obtained relatively to the movements 

 of the atmosphere and the directions of the lines of equal 

 barometric pressure are taken into consideration. 



