- How French Drains Work (practical.engineering)
In February of 2017, one of the largest spillways in the world, the one at Oroville Dam in northern California, was severely damaged during releases from heavy rain. You might remember this. I made a video about it, and then another one about the impressive feat of rebuilding the structure. In the forensic report following the incident, one of the contributing causes identified in the failure was the drainage system below the spillway. Rather than being installed below the concrete, each drain protruded into it, reducing the thickness of the concrete and making it more prone to cracking.
- Species (plato.standford.edu)
What are biological species? At first glance, this seems like an easy question to answer. Homo sapiens is a species, and so is Canis familiaris. Many species can be easily distinguished. When we turn to the scientific literature on species, the nature of species becomes much less clear. Biologists offer over twenty definitions of the term ‘species’ (Hey 2001). These definitions are not fringe accounts of species but prominent definitions in the biological literature. Philosophers also disagree on the nature of species. Their primary concern is the ontological status of species. Some philosophers believe that species are natural kinds. Others maintain that species are particulars or individuals.
