diff --git a/public/js/app.js b/public/js/app.js
index 23b5cab..949cd27 100644
--- a/public/js/app.js
+++ b/public/js/app.js
@@ -2,6 +2,12 @@
 var WIDTH = 800;
 var HEIGHT = 600;
 
+var MAX_DISTANCE = 5;
+var MIN_DISTANCE = 0;
+
+var MIN_DATE = new Date('2016-1-1');
+var MAX_DATE = new Date('2017-1-1');
+
 d3.select('svg').style({
 	height: HEIGHT,
 	width: WIDTH