The history of the 1912 boycott
Before the fall of the Qing dynasty in 1912, Guangdong province had a mint that was nominally under Beijing's control, but in fact ran more or less autonomously. It minted coins that were supposed to correspond in value to the Mexican silver dollar (which was the global standard for silver coins); so did Hong Kong, and theoretically these coins should have been of equal value. The mainland coins were not legal tender in HK, but lots of shopkeepers and merchants accepted them, anyway -- both for convenience and because the HK mint never produced enough currency for the population's daily needs. The Tramways and the Star Ferry were two of the bigger firms that accepted these coins, collecting thousands every day.
But in fact the Guangdong mint cut corners, so its coins had about 5% less silver in them than HK coins. This meant that it was profitable for people to use Guangdong coins in HK whenever they could get away with it, hoard HK coins, and then take them to Guangdong to be melted down and re-minted into 5% more dollars than they had had before. This had been going on for years. It created a small loss of earnings for the Tramways and a nuisance for the HK government (because the drain of good coins from HK to Guangdong exacerbated currency shortages). The company had periodically asked the HK government to stop the influx of these coins; the government replied that the coins were already not legal tender, so the company should just not accept them. And so the status quo continued.
In 1912, with the fall of the Qing, the new government in Guangdong became more independent of the central government than before; it continued printing underweight coins, and was also running a considerable fiscal deficit, which it was trying to get HK merchants to finance. The HK government opposed this, and also seemed concerned that the new Guangdong government was too politically and socially radical; in this context, Hong Kong officials became more vocal about encouraging HK merchants to stop accepting mainland coins. (It’s also possible that the new Guangdong government, given its financial problems was underweighting the coins even more than before, but this is not clear.) So on November 18, the Company suddenly instructed all its personnel to stop accepting these coins.
This infuriated many people, especially poor people – many of whom used the trams to commute to work, since it was the cheapest form of transport other than walking. Not only did they lose the chance to pay with underweight coins (which some employers provided for this purpose); because Hong Kong had a perpetual shortage of its own small coins (since the government didn’t mint enough), people who couldn’t use mainland coins often couldn’t find small coins to pay with at all. Moreover, many people felt that the Company’s unwillingness to take mainland coins that they had long accepted was an insult to the new Republican government, and to China in general – in fact, the “insult” issue played a much bigger role in public sloganeering and explanations of people’s anger than whatever economic hardship the rejection of these coins caused. Calls for a boycott of the trams emerged almost immediately. The company and some workers tried to keep the trams running, but in some cases these trams were surrounded by angry crowds; stones were thrown at passengers, workers, and the trams themselves. (There were over 1,000 people in one such crowd, on November 25).
The Company did not budge, however. It kept the trams running, though during the end of November, December, and early January, they were generally almost empty and required police protection. Meanwhile, the government stepped in by passing a Boycott Ordinance that put tremendous pressure on the protestors, in two ways. First, the Ordinance made it a crime to commit “any act calculated to persuade or induce any persons not to make use of or occupy any moveable property in any lawful manner, or not to work for any persons in a lawful manner”: wording so broad that it not only covered throwing rocks and blocking the tram tracks, but even peaceful speech in favor of the boycott. Second, it empowered the government to declare any area of the city to be a “boycott area,” and place a special tax levy on that area – essentially a collective fine upon the residents of a designated area. (Some of these funds could be used to reimburse any person or entity that had been harmed by the boycott – a measure obviously designed to encourage the Tramway Company, other firms not accepting mainland coins, to not give in to the protests). On January 4, Governor May declared most of the areas along the trams’ routes to be boycott areas, and gave them 12 days to solve the matter before the special levies would begin. Chinese merchants in these areas, who would have paid most of these costs (and many of whom were already being hurt by the boycott) began to press for an end to the boycott, while also persuading the Company to make a largely symbolic concession by selling the merchants slightly discounted tram tickets that they could the use to lure back riders. By the end of January, the boycott had petered out, and in early February, the Boycott Ordinance was suspended.