Ambient TypeScript Modules in node.js

I'm trying to write an ambient module in node.js using the Visual Studio developer tools.

The module looks like this

module "Module" {
   export class Class {
       first = "First";
       second = "Second";
   }
}

I think attempt to use this in another file:

var m = require("Module");
var c = new m.Class();

The typing on the require statement is fine, but this gives a compiler error, saying "Only ambient modules can use quoted names".

How then am I supposed to write my TypeScript modules such that they can be imported into other project files, and the import is strongly typed?