Further notes on the rainfall of Singapore
J.J.L. Wheatley published this follow-up study on Singapore’s rainfall in 1885, presenting a consolidated dataset from seven observation stations covering 1869 to 1884 and examining the relationship between rainfall patterns and public health outcomes, particularly cholera and beri-beri epidemics. The article serves as both a meteorological record and an early argument for systematic scientific observation in the Straits Settlements.
Summary
Wheatley’s earlier 1880 notes relied on only two rain gauge stations—the old Criminal Prison and Mr. Knight’s residence on Mount Pleasant—both of which had been discontinued by the time of this follow-up. He now draws on records from seven stations, accessed through the courtesy of Dr. Rowell, Principal Civil Medical Officer of the Straits Settlements, to produce a more representative picture of Singapore’s mean annual rainfall (p. 60). The data reveals a pronounced long-term decline: from 123.24 inches in 1869 to 58.37 inches in 1884, with the lowest point recorded in 1877 at 89.91 inches and a notable recovery in 1878 to nearly double that figure (p. 61). The number of rainy days follows a similar trajectory, falling from 209 in 1869 to 119 in 1876 before partial recovery (p. 66).
Wheatley engages directly with Mr. Skinner’s earlier hypothesis in the Journal that rainfall fluctuations could be correlated with outbreaks of cholera and beri-beri. He acknowledges the chart’s apparent support for Skinner’s prediction of excess rain in 1884–85 but cautions that several more years of data are needed to establish any rhythmic pattern of alternation (p. 61). More importantly, he argues that the marked improvement in Singapore’s sanitary conditions over the preceding eight years—particularly the completion of the water-works under Messrs. Bayliss and Colson—makes it “hardly fair” to attribute differences in disease incidence to rainfall alone (p. 61). The 1873 cholera epidemic, he notes, was compounded by an unusually dry season, failed aqueduct infrastructure, and the resort of poorer residents to filthy canal water, with the worst cases concentrated along the canal from the Lunatic Asylum through Kampong Kapor to Rochor (p. 61).
The article closes with a broader advocacy for institutional scientific infrastructure. Wheatley proposes the establishment of an observatory under an Astronomer and Meteorologist, arguing that Singapore’s equatorial position offers a uniquely valuable field for astronomical observation (p. 62). In the interim, he suggests that police sergeants at stations in Changi, Tanjong Karang, Bukit Timah Road (7th mile), and Selitar could maintain rain gauges, and notes the absence of a central island station as a significant gap given that the streams feeding the town’s impounding reservoir are fed by rainfall on the southern aspect of Bukit Timah (p. 63).
Key Findings
- Mean annual rainfall declined from 123.24 inches (1869) to 58.37 inches (1884), with 1877 recording the lowest figure at 89.91 inches and 1878 showing an almost doubling to 111.08 inches (p. 65).
- Mean annual rainy days fell from 209 (1869) to 119 (1876), with a partial recovery to 167 by 1883 (p. 66).
- The 1873 cholera epidemic was spatially concentrated along the canal corridor from the Lunatic Asylum through Kampong Kapor to Rochor, areas deficient in water supply and sanitation (p. 61).
- Completion of the water-works by Bayliss and Colson in 1875–77, including the use of a steam engine to pump water across the canal, coincided with the end of epidemic cholera in Singapore (p. 62).
- Monthly means show December as the wettest month (10.23 inches, 18 rainy days) and February the driest (6.14 inches, 13 rainy days) across the 1869–1884 period (pp. 66–67).
- Wheatley identifies the absence of a rain gauge station in the centre of the island as a critical gap, since the streams feeding the town’s drinking water reservoir are fed by rainfall on Bukit Timah’s southern slope (p. 63).
Conclusion
Wheatley’s definitive takeaway is that while rainfall data is accumulating and may eventually reveal periodic patterns relevant to public health, it is premature to draw causal inferences between rainfall and disease without controlling for the concurrent and transformative improvements in water supply and sanitation. The article functions as much as a plea for institutional investment in meteorological and astronomical observation as it does as a meteorological report, positioning Singapore’s equatorial location as a site of particular scientific value that warranted dedicated infrastructure.
Context
- The article was published in the Journal of the Straits Branch of the Royal Asiatic Society (JSBRAS), the predecessor to the Journal of the Malaysian Branch of the Royal Asiatic Society, reflecting the colonial scientific community’s interest in local environmental data.
- The rainfall records were maintained by the Principal Civil Medical Officer’s office, illustrating how meteorological observation in the Straits Settlements was embedded within the medical and administrative apparatus rather than a dedicated scientific institution.