Changing the perception of time: railroads, inventor access and innovation in 19th-century France
利用19世纪法国铁路扩张的历史，研究发现铁路通过降低区域间移动成本，增强了发明者之间的知识传播，从而促进了专利活动，尤其在农业和中等城市中效果显著。
I exploit an episode in French history to study the relationship between the rollout of railroads and the rise of the innovation activity in French regions, proxied by the number of patents registered in the French historical database. I employ an inventor access mechanism to show that, by reducing the cost of moving between regions, railways intensified the influence exerted by neighbouring concentrations of inventors, thereby triggering the spread of knowledge and subsequent patenting. I find that inventor access significantly boosts patenting activity, particularly in agriculture and in medium-sized cities. Finally, I study the role of a global city, such as Paris, on the diffusion of new technologies and report evidence that it uniquely enables smaller cantons to branch into new fields of innovation. By contrast, other major cities do not exert a comparable influence. These findings shed new light on how infrastructure development shapes the spatial dynamics of innovation.